I think it may help newbies to find their first step
If you don’t know what is your playstyle. May be you should take a look on some youtube videos and figure out which animation and effect type you like. (Then you can choose from skills or damage type)
A) Nearly everything can work (not all can do everything) as long as you follow a 2 out of 3 for damage.
You get two classes + 1 set of devotion. You will need Damage Support from two of those to kill fast enough. Either both Classes or 1 Class + Set of Devotion (if the damage type support is there from Devotion). The third one should look to cover defensive weakness. The damage type that are well supported in Devotion often end up with a 2nd class that offer only Defensive (and/or a big Resistance Reduction) help.
I would also point out that Occultist got some massive Skill (Possession - Blood of Dreeg - CoF) that can help a lot of class. DoT in that game is (IMO) massively strong compared to other ARPG so Poison or Burn are even 2 option that are totally viable.
So Pick one skill that you like check the damage type that it has and check if Devotion can give you enough edge in term of damage. If it doesn’t you will need to go Defensive and pick a 2nd class that will help the damage.
You will see lot of Poison (Occultist + Devotion) and Fire (Demolitionist + Devotion) as “beginner” friendly cause you can then pick a 2nd class purely for the defensive aspect of the game and cover the weakness created by lacking gear.
Well, GD has much slower gameplay than PoE, with ACTUAL fight between player and enemies even in lategame (in PoE, player is meant to oneshot enemies from afar, before they could even react, or let his totems/summons do the same).
There are certain relativelt gear-independant builds, like vitality Conjurer, etc.
You can also play 1-h+shield physical Cadence Witchblade, i assure you, even without those legendary sets, he’s a formidable character that can push you through the game and farm all gear he needs himself. With endgame items, he’s THE strongest one build in GD, that can beat any realistic challenges.