I find that it helps to watch games that other higher rated players play .You can see how they develop their pieces and always have pieces that are protecting their other pieces , no unprotected "Hanging Pieces" . Meaning pieces that can be taken freely by your opponent.
Also don't exchange pieces when you are down , only when you are up and have more pieces than your opponent has. Also watch out for smothered checkmates . Make sure the King always has a place to move to avoid checkmate.
What is ironic is that I didn't follow my own advice. I just lost a game due to smothered checkmate.
I have analysed a game you have played (a game you won, as your higher rated opponent made more mistakes than you (almost every move played in this game had a major or minor mistake), and will post it here for educational reasons when I have time to finish the analysis (after a few hours), although the main lesson can be learnt without analysing the game at all.
chess dot com reports the game as "60 min rapid" which is obviously not correct (all games with total time over an hour are not rapid), it lasted 35 moves, and your opponent consumed a bit more than nine minutes, while you ended the game with eight and a half minutes thinking time.
What's the point of setting the game at 60 minutes when you play so fast? And more than that, how do you expect to get above beginner level when you consume an average of 15 seconds per move? The only thing you should expect for sure is making serious mistakes, and repeating them again, and again.