How to Decide what Move to Play

1. Material
If you are having more material --> Endgame is better --> Exchange Pieces, especially Queens
If you are having less material --> Middle Game is better --> Avoid Exchanging Pieces, try to Attack

2. Pawn Structure
If your Pawn Structure is better --> Endgame is better --> Try to Exchange Pieces, especially Queens
If your Pawn Structure has Weaknesses --> Middle Game is better --> Avoid exchanging Pieces, try to Attack

3. King Safety
If the enemy K position is weak, do not worry about Material or Pawn Structure --> Try to open Lines and Attack the enemy K (even sacrificing Pieces or Pawns is OK), go for Checkmate
If your own K position is weak, Protect your K with your Pieces, be careful which enemy Pieces are trying to Attack --> Try to exchange the enemy Pieces that are on strong Sqs