middle game book
For tactics I suggest a website such as here or Chessable for example, do 5 to 10 a day. I find more than 20 and I get lazy and start guessing the solution which is counterproductive. For middlegame, I found Amateur's Mind by Silman very helpful. As well as instruction it includes 25 middlegame tests where you come up with a plan for the position. Silman gives fully annotated answers which run to nearly 100 pages.
Good Chess Books for Beginners and Beyond...
https://www.chess.com/blog/RussBell/good-chess-books-for-beginners-and-beyond