For real just playing the game you will learn. Nothing you find playing through the campaign until youre in like maybe act 4+ is gonna be worth a crap. Max item level is like 82 which is what you want for crafting. I wouldn't worry much about understanding crafting through the campaign. Slam some orbs, make some gear to get you through the acts and read everything. New player this season myself (bought when launched on ps5 but didn't bother playing on there lol)
Skill and support gems drop alot so dont be afraid to try different skills
Passive tree just aim for things that make sense with what youre doing and dont forget armour/energy shield/evasion nodes. Defenses and resistance seem to be important in this game.
My best suggestion is if you need help getting through the campaign, get to the trial of sehkemas in act 2 and pay for someone to run you through the 8point service,if youre a huntress (not sure about other classes) you want to use those 8 points in the spirit walker class. When you enter act 3 find silver fist monkey in jungle ruins tame him. The rest of the game sails.