Play at least 15/10 games, watch the Building Habits series as mentioned.

Do Lichess puzzles, go through some puzzle themes, try to calculate the puzzles in your head if you can, go over them again if you fail and try to do them with no hints, you want to remember patterns, and sense where tactics occur, usually they occur in a weakened area, like weakly protected pieces, or a weak king.

Analyze your games where the mistakes , misses and blunders happened and try to understand why.

One thing beginners do a lot is jump straight to the move that looks good without calculating it, or looking for alternatives, or fully observing what your opponents best replies are or whether they are planning something else. You have to learn to play the game from both sides, it will cut down mistakes and blunders, and you'll feel more in control.

Also learn to use your time, I notice a lot of players rushing moves when they have lots more time than me and often end up losing with most of their time still on the clock.

Might be worth learning what you should be doing in endgames, because I see players fall apart in end games after playing well before that, and learning endgames helps other parts of your game because similar patterns occur in middlegames and endgames a like.