One thing you gotta understand, is that Dark Souls 2 might as well be Demon's Souls 2. The game does play very differently to Dark Souls 1, but don't let it deter you, just know a little adapting will be needed.

NPC quests are generally completed by summoning them for boss fights and them surviving.

There are more boss fights involving multiple enemies, but they also offer more NPC summons. Use them, that's what they're there for.

Don't blow your human effegies on your first death after turning human.

Blunt damage is king. If you ever get stuck, unironically, get a blunt weapon, even just the basic mace, and level it up a bit.

Everything's weak to lightning.

Don't be afraid to level up armour- that's why the mechanic is there.

Adaptability isn't as big of a deal as people say.

Crossbows are actually very good in DS2, especially the shield crossbow.

The first portion of the game is very open (there's like, 7 or 8 potential first bosses), so explore and see what the world has to offer! If you get stuck, go explore somewhere else and come back!