In the middle of the game try exchanging pieces
Is QGD Best for Post-Beginner to Learn?

I think the best for post beginner is to leran whatever defense appeal to them. As long as it is not some joke/trash defense like englund gambit (1.d4 e5) or polish defense (1.d4 b5).
When you see some games played with an opening you like the positions of, learn it and play it.
Am I alone in this opinion.
Also way to learn an opening in my opinion is to learn the typical strcutures, ideas and plans of the opening first, only later learn theoritical moves. A method a vast majority of openings books unfortunately do not use.
The best way to win will be block other pieces to move by using pawn