Preferably, you'll want to go with a class with a high ADP stat, or Adaptability.
If you didn't already know, Adaptability is a DS2-Only stat which governs your dodge and back-step
I-Frames, and speeds up certain Animations, such as drinking Estus and using Lifegems.
If you choose a class with low ADP, don't worry! Levelling is really easy in DS2, as the enemies drop lots of souls.

For your Starting Gift, you have two options:
1) Healing Supplies: A collection of Lifegems, healing consumables exclusive to DS2, with which, unlike the Estus Flask, you can move while using.
2) Bonfire Ascetic: This item can be burned at a Bonfire to make that Bonfire's corresponding area scale up to New Game Plus. I recommend you only use this if you have cleared out an area and didn't join Covenant of Champions*, or if you want to fight a boss again.



*More on this later!

After choosing your starting class, you're likely going to be figuring out what build you want to go for, but before you pump all of your souls into Strength, Dexterity, etc., there are three stats which should take Priority:
-Vitality: Raises your maximum equipment load, helping you stay in mid or light-roll territory. The Fat-Roll Threshold is 69.0% Equipment Burden, so try and stay below that.
-Endurance: Increases the amount of stamina you have. Stamina is very important across all of Soulsborne, but in DS2, your actions take up a lot of stamina, and you don't start with a lot, either.
-Adaptability: As I mentioned before, this DS2-Only stat governs your dodge I-Frames and animation speeds, and with DS2's rather janky or uneven hitboxes, you'll want as much chance of avoiding hits as possible.
You're probably wondering why Vigour isn't among your top priorities, and the reason is that all three of the stats mentioned above grant slight increases to your HP as well!
After hitting 25 ADP, you can remove it from your list of priorities if you want, as you will have what the Soulsborne Community considers "acceptable" I-Frames.

DS2 has a raft of weapons which are accessible from the start and can still carry you through the entire game. Two examples are the standard Rapier, which deals unreal amounts of damage for its speed, if you choose a Dexterity Build; and the Mace, which also deals unreal amounts of damage for its speed, but works best for a Strength Build. To acquire these weapons, you first need to make it to the Forest of the Fallen Giants, (the route to which you should search for yourself for that feeling of discovery!) and grab the Bonfire so you can return here later. After you grab the Bonfire, talk to the NPC next to it. She will sell you Lenigrast's Key for 1000 Souls, which opens the Blacksmith shop in Majula, where you can buy the mace, rapier, and other weapons for 800 souls each.

Power-Stancing
Power-Stancing is another mechanic unique to DS2, where if you have two of the same class of weapon (i.e., two hammers), one in each hand, and 1.5x the required stats to wield them, you can use the same input to swap to your left-hand weapon* to use a special dual-wielding move-set. Now, keep in mind, while Power-Stancing increases your damage output, it also drains larger amounts of stamina than just wielding one.

*For Controller players, this would be holding down "Y" for XBox controllers and Triangle for PS4/5 Controllers. Speaking of which, Soulsborne games are best on a gamepad, as the first of them was an XBox 360-exclusive, only Ported to PS3 and PC a while afterwards, therefore designed specifically for controllers.

The first boss you'll want to go for is The Last Giant. Despite it's intimidating name and unsettling appearance, The Last Giant is a very easy boss. Defeating him will award you with The Soldier's Key, which can be used to access the next boss on our hit-list: The Pursuer.

The Last Giant's Location:
https://youtu.be/2uDjfcjCk5Q?si=e1uJpqMPCxMNceLR

The Pursuer is a big step up from The Last Giant; he has a far more varied move-set, which makes him a rather enjoyable boss in my opinion, and lots more health. But, defeating him awards you with the Ring Of Blades, which increases physical attack power by ~20%, and 20K souls, which you should spend on Vitality if you want to use the next item! After defeating The Pursuer, a small area will open up behind him, search around for a bit and you'll find a corpse with loot. Looting this corpse will give you:
-Drangleic Chest, Boots, and Gloves
-Drangleic Shield
-Drangleic Sword
All of these items are quite heavy, hence the vitality you should level, but the armour offers high DMG negation and the weapon can do lots of damage on a Strength build, provided you're open to Dexterity investments.

The Pursuer's Location:
https://youtu.be/Wc89e1puw9M?si=v6EddA_cYl24P874

If you aren't confident in your ability to beat a boss, then clear out the boss's run-back. In DS2, unlike the rest of the series, the world can be cleared so no enemies respawn. For example, if you kill one enemy ~15 times, that specific enemy will stop respawning, unless you joined the Covenant of Champions back in Majula.
This Covenant removes the respawn limit on enemies, which can be both a blessing and a curse; on the one hand, you can farm the enemies for souls infinitely, but on the other hand the boss runs will remain uncleared.
If you joined this Covenant and want to clear out the boss runs, simply return to Majula, and speak to the NPC at the monument on the edge of Majula. He asks you if you want to join the Covenant of the Meek. This Covenant keeps the respawn limits AND gives you a ring which increases HP right off the bat, as well as summoning a Knight of Blue to help when you get invaded*.

*More on this later!

In Dark Souls 1-3, there is a mechanic called Invasions, where another player can join your world with the goal of defeating YOU, without any warning, at any time (unless you're in a boss room). So not to run the risk of this, STAY ALIVE to the best of your ability, and use a Human Effigy consumable to reverse your Hollowing when you die. Being Hollow allows for more open Cooperation, but also allows you to be invaded.

There is also Cooperation, which can be initiated at your own will via an item called White Sign Soapstone. This item can be received from Pate, an NPC you can find on your way to the Last Giant. Talk to him, exhaust his dialogue (wait until he repeats the same sentence over and over again) and then go through the gate next to him. It will close behind you, and a group of Hollow Soldiers will come out to attack you; you have two choices: allow them to kill you, and respawn at the Bonfire, or Kill them and progress through the building. Both of these courses of action will trigger Pate to give you the Soapstone.

To use the Soapstone, first make sure you are online; you can tell if you are online if you see Messages and Bloodstains around the area. Go to an area with enemies (i.e., not Majula) find the item in your inventory, select it and press "Use". This will place down a Summon Sign, with which any player can summon you to their world to help them. If another player places down a Summon Sign and you interact with it, you can summon that player to help you beat the area Boss. Keep in mind that you can summon NPCs if you are offline, but they are far less useful, as their AI is programmed to dodge sparingly, otherwise they would solo every single boss completely hitless.

Another form of Cooperation is initiated through a ring given to you for joining the Covenant of the Meek, A.K.A the Way of Blue, which pulls in another player of the same covenant Covenant to help you defeat an invader. To be pulled in to help, you must first defeat the Old Dragonslayer boss in Heide's Tower of Flame, after which is an NPC who is your ticket into helping victims of this annoying mechanic. (In my opinion, the only things in this world worse than death, are the "people" who wake up and choose to ruin your day.)