New Necromancer to Diablo Any Advice?

I decided (for reasons I still don’t understand) to download Diablo 4 thanks to PS Plus over the weekend and well… I’m addicted. So I have taken to an exploding blood mist build and I’ve already take the difficulty up to hard but when I go up another level in difficulty I’m getting pretty crushed… I’m level 41 as of this moment but what are some things I can do to either buff my build or what are some builds I should try?

Also… any tips for a new player? Any common mistakes new players make that I can avoid?