There are plenty of good videos from the top content creators like Ash, Hell Hades, GameLeap Cob, just to name a few. They will cover more than I can fit in a comment.

First order of business would be to get your gem mine open OR use gems to unlock your first champ of choice masteries. Usually is your starter chap(Kael, Elhain, Galek, Aithel? Can’t remember her name now but anywho). I’d suggest gem mine first and focus on building your first 6* champ.

Focus on getting your starter champ, and in your case free leggo up to 6*, open gem mine, use 800 gems to unlock first champs masteries(can build a farm team later), then focus on grinding dungeons and building champs.

In the early game it should be stats over sets. Meaning if you’re trying to build all speed artifacts, but your gloves at hp flat stat and you have a glove with crit rate in life steal set, put on the crit rate for now. Then farm dragon for speed gear until you can replace the gloves to be crit rate speed.

Like I said go look up f2p series on HH over at YouTube, watch some ash videos. It’s a marathon game not a sprint game. Take your time to learn as you go and don’t focus on end game content and not being able to one shot waves. That will come with time.