The Art of the Middlegame: Key Strategies and Common Mistakes

Don't blunder, focus on your pieces and your opponent's pieces as well
so u mean like only doing moves that will win pieces or something and try to stay even in pieces more?

You're in luck. I wrote an essay on exactly this topic: how to formulate a middle-game plan.
GM Larry Evans' method of static analysis - Chess Forums - Chess.com
Read my posts on page 1 of the thread - specifically, posts 4, 7-to-10, and 12.
Then play over the three sample games on page 1 and 2, reading the annotations.
I'm seeking advice on improving my middlegame play and would appreciate any insights or tips from the community. Despite having a good grasp of opening theory and endgame principles, I often find myself struggling to formulate a solid plan during the middlegame. I’m particularly interested in learning about key strategic concepts that can guide my decision-making, as well as common mistakes that players should be wary of. Additionally, I’d love recommendations for resources—such as books, videos, or training programs—that can help deepen my understanding of this critical phase of the game. Any practical examples or personal experiences you could share would be immensely valuable. Thank you in advance for your help!