1) The Name of The Game Is Efficiency
You need the biggest returns for the least investment. Always look for the most efficient way of doing things.

It generally pays to spend as much time on a single activity as possible, and to max your bars when restoring something. That way, you spend LESS time and money traveling between locations on the map, and more time actually doing things. You also spend less money entering the gym if you spend extra time there.

2) Fight or Die!
You gain skill points by fighting. Skill points grant you more powerful abilities that let you win fights, which grant more skill points. Fight as often as possible in the Bar League, Rookie/Scoring League and any other special fights available to you.

You should be either pad training or sparring with Silver every day, if possible. The extra 2-3 skill points add up over time. Use pad training at the start: you gain nothing if you spar and lose.

Make sure, however, you keep your health up, particularly when walking into the Underground Ultimate Fighting league, since injuries are expensive to treat.

3) Don't carry more than $150 if you don't want to be mugged.

The muggers are serious business. A few of them are push overs, but a lot of them are incredible asskickers who could make more money as illegal fighting than mugging. You don't really need to carry a ton of cash with you anyway.
Note: Patches have rendered this advice irrelevant.

Get up, and answer the phone

Walk into the other room and do pushups. Note that this is the first and only time you should ever use your house's training room. The Gym is far more efficient, even with it's $10 training fee.

Go back and hit the fridge. I recommend Soda for breakfast.

Use the newspaper to get a job you'll never actually do.

Walk to the construction site.

Get mugged. This is unavoidable, and you can't possibly win this fight. You'll get hell beaten out of you no matter what you do.

Now you get to select a starting trait.

Basically, there are three paths in this game. Agility uses path of the tiger (and is the simplest). Strength uses path of the bear (and is relatively simple). Stamina uses path of the turtle (this is a little more confusing and takes a while to get going).

Strong Arms is good for Bear, and Turtle.
Strong Legs is acceptable for Tiger, and Turtle.
Skinny Guy is utterly amazing for Tiger, and utter crap for everything else.

Note that, if you are planning on taking Tiger, make sure one of your starting abilities is dodge. This is very important. You should restart if you don't get it. If you are picking Turtle or Bear, make sure that one of your starting abilities is Block. Restart if you don't get it.

Now go to the market, and buy a bunch of Frozen Pizzas with all your money.

Head to Mick's, and talk to him. After he's done talking to him, tell him your are broke and hungry. If you ate soda and spent your cash on frozen pizzas, that should be right now.

You can come to him 3 times so long as you have under $10 or so in your wallet and are very hungry, even if you have food at home in your fridge. You should totally use these to gain a little more efficency in the early game.

Go to the Gym. You can chose to skip sparring with Silver if you want. Join the rookie league.

Go home and eat pizzas and maybe rest. That should be the first day or so.

Head to the market. Apu will tell you about a cafe that is looking to hire a delivery man for their pizzas. Go to the cafe, and take the job there. This is a way more efficient a money maker than the construction job.

Arrange a nearly full energy/hunger bar, and $10, and hit the gym, and try and raise your chosen stat by 1 or 2 points before you hit the first fight.

On the day of a fight, the Fist Icon will flash an exclamation mark. You can select it and hit fight to teleport to the Gym. If you don't select it, at the end of the day you'll be forced to fight, with some minor reductions in stats from stat decay.

After every fight, you'll gain skill points. Try to only buy things that are vital to you, as every bought ability increases the amount of points you need to gain the next one. You want to get to your "technique" as soon as possible, and concentrate in one area.

"What's the best way to regain hunger?"
The market has the most efficient food available.

Meat is the most efficient at $20 for 40 hunger points. Two of them will take your from a sliver of hunger to near max.

Pizzas are only slightly less efficient at $9 for 17, and have two advantages over meat.
1) They restore way more health per $, so if you are injured, buy and eat a ton of pizzas.
2) They can "top off" your health bar, where as meat restores so much that it's easy to waste points.

Since it's most efficient to top off your hunger bar (or get as close as possible) to work/use the gym as long as possible with one visit, you want to use both of these. Sodas are inherently terrible, and should be avoided. Energy bars are inefficent, since the cost of buying them is usually worse than paying the gym fee.

"What's the most efficient way to training stats?"
The Gym offers the most efficient training, by a wide margin, over the stuff available in the garage. You have to work for a long time to afford any of the garage items, and there's a good chance you'll be mugged if you try and buy a $250 item anyway.

I've tried, and honestly, it still wasn't as good as going to the Gym.

The other thing to realize is that stats drop after every day (and drop more the higher they are). You can minimize the losses by concentrating on one or two stats at at time. Stats can't go below one, and there's plenty of machines in the gym which allow you to concentrate on just one or two stats.

You can also take advantage of the "memory" skills, which raise the "mininum" value of your stat. For example, you could raise your strength to 4, take "Muscle Memory" and then spend the next several days doing nothing but raising Agl and Stamina. The losses to strength would be ignored, since your strength can't go lower than 4.

Keep in mind that, raising stats (particularly strength!) isn't always inherently good. Strength raises the stamina cost of your attacks, so don't overdo it unless your style can take advantage of that. For tiger specialists, there's lots of moves that do damage irrelevant to your strength, so it can actually be more efficient to be a tiny str 1 weakling. Of course, having a 0 agility is very painful, since you'll rarely hit and rarely dodge.

Know what the machines in the Gym* do.
Bench Press - Raises Strength
Lift Bar - Raises Strength
Squat Rack - Raises Strength and Endurance
Speed Bag - Raises Speed
Treadmill - Raises Endurance
Jump Rope - Raises Endurance/Speed
Tire - Raises all stats a little
Heavy Bag - Raises all stats a little

*- Pretty sure I'm misnaming these. I don't even lift, bro.

You can concentrate on one or two stats by using the right combination of machines. For example, an agility build can use Speed Bag + Jump Rope and then a bit of teadmill until Speed Bag is "recharged".

"What stats should I raise?"
Read the next section. The short answer is, probably all of them, particularly the one for the technique tree you are specializing in. Agility builds can ignore strength.

"Should I use the bus or walk?"
I'm not 100% on this, but I think there's a minimum time unit a trip can take (1 time unit). I generally take the bus if it costs $1 and sometimes $2, but almost never if it's $3 in the early game, unless it would take 2 or more time units to get to the location.

Late game, you have a ton of money from Ultimate Fighting/Gang Warfare/Movies and can almost always take the bus.

"How I unlock ultimate fights?" [/b]
After you win 2 rookie league fights, go into the gym and spot for the lifter. He'll tell you about the league.

"Any tips on restoring energy?"
It seems to take "time" for the energy gained when you use the bed to get to your bar the top. You want to wake up before the bar hits the top of the screen to avoid spending unnecessary time sleeping.

"What stats should I raise and what do they do?"
It depends on your build.

Tiger Builds need agility, and a bit of stamina. They can ignore strength totally if they want, though a few points will increase their damage. I'd go with 1, maybe 4 if you get muscle memory.

Bear needs high strength and decent stats in everything else. If your agility is really low, you'll rarely hit (though it's possible to specialize in very accurate strikes to mitigate this). Definately take a decent stamina, and if you are still running out, add "wait" to your combat skills for the extra energy.

Turtle stats need high stamina and decent stats in everything else.

"What Skills should I buy?"
Whatever gets you to your technique quickly. It's almost never worth it to pick up the early basic skills, except (perhaps) "Skip Attack" for Bear Style, (because Bear has energy problems).

In general, you want to get to the "technique" skills as quickly as possible, since the skills in the technique section (usually) are more powerful than the basic ones.

Skills come in two varieties - Active moves (attacks, defenses and utility powers) that have to be slotted to be used, and techniques. Techniques are generally more useful. You don't have that many slots available, and most builds concentrate on one or two attacks, one defense and maybe one utility in the late game.

Look for the best attack, given your stats. This is kind of hard to figure out, but the flavor text and the position on the tree help you figure out what's going to work well for you. As an example, an attack that "doesn't require much agility" and appears in the Bear tree is probably going to be better for a strength build.

I'll be looking at recommended build paths a bit later in other sections.

The main point is that, because costs increase with each skill, you want to be very careful about what skills you take. Look at the tree and figure out what skill will help you the most and what you should be aiming for right now. Don't buy slots if you lack an ability you really need to use, and don't buy weird abilities that will require slots you don't have. If you can, try and head to later skills as fast as possible: don't take multiple early powers since it'll delay getting the powerful capstone abilities.

"Are Debuffs any good?"
Some of them seem horribly broken, as in they don't work, at all. the +30% energy one vanishes off the enemy tool bar a second after it hits. Even if you doubled the duration it it wouldn't be worth it. Cobra Strike (end of the agility tree) seems to last forever, even over multiple rounds, and is really powerful if you can actually hit with it. I don't really have a good answer to this one.

"Are the Magic Potions worth using?" Will they screw my endings up?
In addition to the obvious benefit of gaining two points before a fight, you can use the +2 to take "memory" feats. Since the scores can't drop below those values, this is a way you can make these bonuses permenent. Plus some of the dialogues are really funny. They don't seem to change the ending.

Combat stats and what they do

Stamina: Determines HP, energy regeneration, passive damage resistance. You do not want to run out of energy or health.

Agility: The higher your agility is compared to your stamina and strength, the more likely you are to hit. The higher your agility is the more likely you can dodge if you use that defense.

Strength: How much damage you do, how much energy attacks cost. Strength raises damage by a huge amount, but it also increases energy costs and makes attacks less accurate.

HP - How much damage you take before being knocked out. While this is influenced primarily by your stamina, it also seems to be affected by your health, energy level, hunger and happiness*. To maximize your HP, go into a fight with a good score.
* (Not sure about the last three or how much)

Defenses and what they do
Block - Takes off damage off each hit.
Dodge - Gives a chance for an attack to miss entirely, based on Agility. Costs energy. Incredibly good if you have a decent agility.

Energy: Every attack you make costs energy. Your max is always 100 (Thanks Taki!) Every time you get hit by an attack, you lose energy. Energy recovers naturally as the fight progresses, and you also recover some when knocked down or a round ends.

If you run out of energy, you'll take a large amount of damage, get knocked down and then get back up with a bit of energy.

There are some builds that count on this and will tire you out with constant debuffs. It's a good idea to make sure that your combat strategy doesn't burn through too much energy too quickly, and if you keep raising strength, your energy consumption can get out of hand.

How to figure out Move Statistics
Damage - Flat Number + Move Damage Multiplier x Strength
Accuracy - Flat Number + ((3xAgl)/(Agl+Str+Stm)) x Move Accuracy Multiplier
Energy cost ?????

Best Starting Perk
Skinny - Because it helps you dodge better.

Stats
An agility build has the advantage that you REALLY don't need any strength, at all, to win. Most of your damage comes from abilities that are independent of strength, like Cobra Strike, Mimic and any Counter Attack Abilities.

You, obviously, need as much agility as possible. The higher your agility is compared to your opponents*.

A good stamina is also useful, because you really can't have too much energy and HP. 6-8 should do. The real focus should be getting your Agl into the stratosphere.

Do NOT raise strength very much. 1 or 2 points is fine, raised strength will increase your energy costs, and tiger is very heavy on energy. Your damage is independent of strength.

Key Abilities
You want a decent kick, usually something that's low energy. Because of your crappy strength, most of the damage will get reduced to 0 late game anyway, so low energy highly accurate attacks are best. Ones that come with energy debuffs aren't bad, either.

Get dodge, a decent kick, and rush to unlock Way of the Tiger. Don't forget to set this up as your "style".

Once you get into the new tree, I recommend picking up the "counter attack" abilities (like backlash). Crossroads (the one that replaces dodge) and Backlash combine nicely to basically do your opponent's damage back to them every time you pull off a dodge.

Get one attack, preferably one that's absurdly energy efficient. It really doesn't need to do a lot of damage, you are just doing it to drain energy from the opponent.

Techniques are good to focus on next, since they represent a permenent bonus to your character.

You may want to get "skip attacks" eventually if you ever have energy problems.

* I don't actually know the formula here, but I seem to dodge a lot less when I'm fighting high agility characters.

Best Starting Trait
Strong Arms, obviously. Way of the bear is all about punch people so hard their soul leaves their body.

Best Starting skills
Doesn't really matter. Any basic attack will do for the first fight or two and you'll unlock (much) better offensive moves quickly. What you really want though is just to make sure you have a starting defence of some kind for the first few fights. I'd say block is better since you won't have a crazy agility.

How Bear Works
Way of the bear hits hard.
It hits so hard that it ends the fight on the first round. Clothesline with 13 strength does incredible damage and hits multiple times with boxer. 80 point combo's are not uncommon, and that's enough damage to even break Ivangief.

Bear has two weaknesses - first, if your opponent is really good at dodging, skills like Backlash will flay you alive because 50% of your damage will end up doing 25-30 per dodged attack on you, and the enemy can dodge a LOT of attacks. Agility builds can be problematic.

Second, if your energy hits 0, you are royally screwed, because the enemy can lock down your stamina with continual light hits, and you'll never get a shot off except immediately after getting up or after a round end (unlikely).

This is why, as bear, you need to
A) Run no defenses and pick up ruthless agression and every attack modifier you can
B) Build your other stats to reasonable levels
C) If you are still having energy problems, use skip attacks every other round.

The key here is to have a reasonably balanced stat build. If your strength gets too far from your agl, you'll miss with every shot you make. If it goes too far above your stamina, you'll be out of breath after a few shots. Try and keep your strength at the highest "muscle memory" zone you can manage so that it doesn't go down, and concentrate on raising agility and stamina. Remember you can use the potions to get those last two stat points. Nice idea before a tough fight or to get the latest muscle memory.

I haven't tried this, but according to some users (thanks Teddy!) you can get away with a pure strength/stm build with a few key skills. Make sure you pick moves that don't really care about agility, and then stack power block wtih the bear counter skill.

Early Skills
Again, obviously, the key is to get up to the "Strength of the bear" as quickly as possible. Once you get in there, get "Clothesline" and "Triple Strike."

Triple strike greatly increases the odds of you getting a "combo" off on an opponent that hits multiple times, and vastly inflates your damage potential. It's really, really good.

Clothesline is (by the numbers they show when you hover over it) the most accurate and damaging power available to this build.

Mid/Late Skills
Aim for boxer and ruthless agression and muscle memory 3. Those are key.

Then I'd grab some attack modifiers (Wreck 'em, Tormenting Blows) and the empty boxes to put them in from the basic tree. Whatever you do, don't grab a box before you have a skill to throw it in, or you'll have to use a sub optimal attack instead of another modifier.

Once you are maxed out, consider long timer for the debuffs and maybe getting Diehard.
Honestly, at this point, you should be able to finish the game, but if you have spare points, maybe grab way of the Tiger: I've heard it's surprisingly good at stopping dodges.

Don't build Turtle. Most of the abilities don't work.

But seriously, to be completed, but I'll probably wait until Turtle gets patched a bit more.

Turtle works, but I don't know enough about it to give a realistic guide. Check other guides.

"How do you fix Roy's car??"
I don't think you can fix it totally, but if you spend a decent ammount of time on it, Roy will spar or train with you. Training wtih Roy while your dating Adrian lets you train stats really, really fast.

"How do you unlock the bar fights?"
Win the first few fights in the rookie league, and a guy named "Roy" will offer to go out for drinks with you. Talk to the guy outside the bar.

"How do you unlock the 'magic potions?"
Lose two fights in the rookie league, and you'll unlock the potion vendor at the sporting goods store. This is worth getting at least once, just for the amusing side effects.

"How do you participate in ultimate fighting?"
Go into the gym workout area after getting a stat of 5+. There will be a big lifter who wants you to spot him. Do so, and he'll tell you about "Ultimate Fighter"

"How do you fight the alligators?"
Get a job delivering Pizzas for Casey. After three deliveries, you can ask him about "Special Spices". Eat the pizza he offers you and he'll give you the job. Continue each time you want to fight one of them.

"How do I build fame?! Any tips?"
One very important one: always save enough fame and cash to do movies. Movies are how you build large amounts of fame and cash. Don't bother too much spending time grinding out the "per day" stuff or + income items, just build up enought to do another movie and a fight or two.

"If I use too many magic potions, will it kill me or wreck my stats or ruin my endings?"
As far as I know, no.

"Apu won't tell me about the pizza shop!"
Buy a couple frozen pizzas from him.

"I keep getting really badly injured in Ultimate Fighter, and I'm loosing my precious gains!"
Don't fight in Ultimate fighter without healing first. You can heal a ton by eating. Shrimp pizzas are expensive, but a good way to recover gobs of health. You can also rest. [/spoilers]

"How do I unlock movies?!?"
Well, it's pretty far in the game. You have to be doing the "win the rookie league" route. If you are doing gang war, you don't get movies. I've only done the legit route myself.