Middle Game Improvement

Hi all, 

Starting to take Chess more seriously and noticed that in my analytics that my middle game is by far my lowest accuracy percentage. Historically, I am better in the end game than my opponents, but feel I can give the game away before I get there. Any advice? Any puzzles on the site to help? Not planning on going pro, but chess is my number 1 hobby now, so wanting to do it right. Will continue to study/practice end games. 

Good Positional Chess, Planning & Strategy Books for Beginners and Beyond...

https://www.chess.com/blog/RussBell/introduction-to-positional-chess-planning-strategy

Study annotated games of grandmasters to understand their thinking process in the middlegame.

Do some puzzles as often as you can, you will spot tactics that win material more easily