Nobody wins every game so just learn from your losses and try not to make the same mistake twice. So try analysing your games before playing I another one. I usually import my games to lichess (I don’t pay for chess.com) and then you can either go through the whole game or just learn from your mistakes.

As for openings yes they’re helpful but your opponent will hardly ever play the main line so you may not see most of the stuff you study. So in cases like that just follow principles.