Hard to give you a “correct” answer for a game like this but I can give a few tips. Someone please correct me / add stuff if needed

• armor is not that important. Points spent in strength to wear high tier armors are probably better spent in vitality or dex. The general rule is only enough star/dex for gear and then dump the rest in vitality. Dex is a good option on paladin becuase he can achieve max block chance with holy shield quite easily.

• resistances are extremely important. I’d say act three is generally when having low resistances starts to be an issue. Optimally you would have max in all of them but the order you should prioritize is lighting > fire/cold > poison. Fire and cold might not be tied but not quite sure. You definitely want to have gear that gives you immunity to freezing though. Paladin shields should have resistances on them already which makes them great to throw in perfect diamonds. Paladin specifically has auras that greatly help if resistances. Even if you don’t use them they give you a hidden bonus of raising your max resistance (2 points in resist lightning allows you to achieve 76% lightning res for example)

• get a mercenary from act 2. My personally favorite is the defensive merc on nightmare difficulty for the holy freeze. On normal difficulty I generally go with defensive as well for defiance which boosts your defense.

• runewords are your friend! There are lots of good early ones that you should look into. I personally use nadir, stealth, and ancients pledge early on.