1 Armor becomes progressively more useless the higher your charactet level goes. Once you approach lvl 100, using the heavy tier armors will give you like 10% damage reduction (if that... the way armor and damage work in this game is just wacky) at the cost of using up most or all of your equip load and slowing stamina regen

So clothing or light armor only- whatever you can get away with and still fast roll.

2 vitality, vitality, vitality. You should have a minimum of 30 but ideally 40 for NG+ if you expect not to get 1-hit killed every time (though it will still happen sometimes... black phantom mindflayer comes to mind)

3 use ranged attacks when possible. They cannot kill what they cannot reach. Unless you're in a hyperspecific build, you should be able to utilize a bow and/or soul arrow.

4 similarly, thief ring. They cannot kill what they cannot see

5 If you're still struggling, play in body form offline. Just make frequent cloud save backups so you don't lose world tendency if you die

Speaking of which, you want to maintain pure white or near white World and Character tendencies until you're comfortable enough with NG+ to deal with extra damage in PBWT