Usually, being bad at middle game can be because you're lacking in development from the opening or failing to capitalize on opponents errors.
1) Make sure you're playing lines you've studied or are at least following opening principles by moving each piece once and castling before you move them again.
Make sure your rooks are connected but don't come out until the minor pieces are off the board or you need to perform a rook raise (a little advanced for your level).
Keep your knights away from the edge of the board. Knights on the rim are grim.
If you put a knight on an empty board on a center square, you have eight options for the first move.
If you put it on an edge you only have four options.
If you put it in a corner, you have only two.
2) For that reason with all of your pieces, control the center. The center gives you options. If it were three dimensional, the center would represent the hilltop on a battlefield.
3) Given your level, I'm assuming you take every time you notice a reasonable opportunity to do so.
Don't.
Take a moment to see if there's a better option.
For instance, this is what I play in the Italian game as white.
Study endgame more than you study tactics. Tactics are good and best really for middlegame but if you know what winning, losing, and drawn positions look like, you can guide your game to and away from those scenarios.
Hope that helps.
hi im playing chess for a while now but i don't see any improvement
if anyone has a tip for a 500 elo player please help
i make many blunders and im bad at mid game, most of the time players just outplay me even if i dont leave my pieces out in danger where they can take them