This game is very non-linear, so a real walkthrough seems pointless, and defeats the point of the game's open nature. I'm just going to put some tips, possibly covering some pitfalls.

First day:
The game starts by telling you that you need a room mate and a promotion. What the game doesn't tell you is that getting the promotion without a room mate is damn near impossible. Go west to the forest, invite Randal to live with you, and *then* go get your promotion.

Speaking of promotions:
When you get a promotion you gain an increased income, but Bob, being dumb like he is, immediately increases spending to match. There is a dungeon behind the "shrine of finance" (upper left corner of your house). Go down there and fight mini bosses to lower your spending. Be careful though because some of them are very tough.
Special note about the health insurance monster: he's immune to everything. You get a work HMO at the end of the fourth promotion dungeon, which lets you one-shot the health insurance monster

Now that I have some income:
you may have noticed the second credit legion is breeding faster than you kill them. Talk to the soldier that offers to give you a rundown on the debt armies. Hear his report, and you get the option to send reinforcements. This is how you pay down debt.

Books for free:
You probably figured this out right after buying some books from the store, but the library will give you as many books as you want for free (in certain types), so go there first, buy a few of each, only buy from the store what you can't get from the library.

Tower of self improvement:
floor of body:
In the section with guys walking up and down, the last set seemed really impossible for a while, but I learned the trick. You have to not be too far ahead of the bottom guy. this gives him time to turn around before the top guy gets to you. If you just go fast you'll lose every time

Floor of society:
the guy on the left side of the chest just wants a sandwich, he sets the rest of the room in motion. A wandering guy also wants a fight. The woman in the upper left corner wants a fetch quest. You won't find that for many hours, and you don't get a reward for turning it in.

From the comments: do sandwich guy last for an optional boss

Third promotion:
This is the promotion dungeon where you teleport by touching candles. There are 3 chests to find, here's how to get everywhere from the first room with a choice:

first chest: Right, Upper left, Bottom
Second chest(tricky): Right, Upper Right, Right, Right, Right
Third chest/boss: right, Bottom Right. This brings you to a large area with four decoy candles. walk down past them. go around the circle for the last chest, and to the candelabra in the middle for the boss.

Fourth promotion:
If you have trouble with the maze just follow the "right hand rule", which means every step you take, try to make a right turn, then if that fails try to go straight ahead, then if that fails try to go left, and if that fails go back the way you came. It's slow and a little tedious, but it will take you to everything important.
There are 4 mini bosses that each give you a veneer weapon. they change your damage to something that can hurt "you know who", but are otherwise pretty terrible. if you have trouble still try a team with a good healer and your 3 best physical attackers. By the time I got here I was able to just attack a bunch. Make sure you get the chests behind you-know-who *before* you fight him. they're both important unique items.

Sailing the ocean:
Turns out the monsters on the ocean are harder than most of the places you can go, so don't be too concerned if they seem *really* hard. The volcano is to the north, and I found it to be pretty easy. the cave in the far east increases your income. Also: you can land pretty much anywhere *except* at the dock.

That's all I got for now. will maybe add more as I think of them

Each Girl requires at very least a letter in order to marry her, some may have other requirements.
Be warned since, of course, this section has spoilers.

Gina:
Red Letter: "Concentrated feelings in the form on a pretty letter that smells of home..."
Found: Talk to her about marriage and she'll give you her letter.

Lisa
Pink Letter: "Concentrated feelings in the form of a flowery letter with a cute pink bow..."
Found: Outside the fortress of discontent.
Take Lisa's letter to her, and she'll inform you that she doesn't swing that way. Maybe there's a way to convince her, but I don't know. This throws new light on her refusing to be your room mate because she's "Living with another girl and it's going pretty well"

Alayna
Blue Letter: "Concentrated feelings in the form of a letter with beautiful calligraphy..."
Found: Bastion of depression

Cecilia
Black Letter: "Concentrated feelings in the form of a letter that's obviously been used as a bookmark..."
Found: In the volcano of Ambition
Brandi
Gold Letter: "Concentrated feelings in the form of a fancy gilded letter on Dungeon of work stationary..."
Found: Behind "you know who" in the 4th dungeon of promotion
Disclaimer: have not yet tried to actually marry her, so there may be other requirements
From the comments: You may need the largest house to marry Brandi