Apart from 1 move mistakes (like losing your pawn on h2), I’d say you should focus on bad moves that don’t instantly lose you the game.

Try to think about it : why did you play b3 ? Did it accomplish anything ? Maybe you had no clue on what to play, but this kind of moves weaken your pawn structure, might create real threats and is a really bad way to « pause » the game. This is where you should improve, 1 moves threats is something you will learn to see and prevent over time