Key Principles for Every Stage of Chess: Openings, Middle Game, and Endgame

The Opening Stage
Since we've already covered specific openings, let's focus on a few key principles:  
- Castle before move 10 to safeguard your king.  
- Avoid moving your king early in the game.  
- Develop your knights before your bishops.  
- Don’t move your queen out too soon.  
- Control the center to dominate the middle game.  
- Keep your knights off the edges of the board, where they are less effective.

The Middle Game
In the middle game, always consider three key factors: checks, captures, and attacks:  
- Checks: Only give checks when they force your opponent to move the king. Avoid checks that can easily be blocked, especially if it leaves your piece vulnerable.  
- Attacks: Try to pin pieces to the king or use lower-valued pieces to attack higher-valued ones.  
- Captures: Capturing pieces can simplify the game, but always check for traps before committing to a move.

The Endgame
In the endgame, the king becomes a powerful piece—don’t leave it in a corner. Actively use your king to support your remaining pieces. Also, check for pawns that could promote to a queen, which can often decide the game.