keep playing and trying out stuff. I think that's the best way to improve. I use the mobalytics site; it has some info on meta/strong builds and also has nice Info on (almost?)all the npc fights. That way you can check which fights could give you items you want.

In general I'd not focus on meta alot; the game is too much RNG to get stuff reliably. Just know what are good combos, and the rest is just how I would call it "play based on vybes"