1.  Develop pieces quickly in the opening and try to get your pieces working together. Try not to move the same piece too many times unless it is absolutely necessary.  It wastes time and it probably means your development is poor.

2.  Play to control or occupy the centre.  A piece is more powerful at the centre than at the edges.

3.  Try to castle early in the game.  The King's side is more favourable, but it depends on your opening.  Try to make your King safe.  The King is more vulnerable to attack or could get trapped if it remains in the centre of the board for too long.

4.  Attack and Retreat but defend only when you have to.  Use only the smallest number of pieces necessary to counter any attack from your opponent.  Try to remain on the attack but be on guard.

5.  When you are stuck and there does not seem to be any sensible move, improve the position of your worst piece.  This may mean either moving it or supporting it with another piece.  Either move should improve its position.

6.  Be sure to look at all the board.  Silly mistakes are made when paying too much attention to one area of the board and ignoring others.  Check those diagonals.

7.  A Knight is a good ally to all of your pieces.  Keep him at the centre of the action either in attack (preferable) or defence.  A knight at the edge covers or attacks less squares.

8.  Before each move ask yourself questions.  Following your opponents move:  Why did he move there? Have I missed something? Does it affect my game plan?  Is my King under threat?  Are any of my pieces under threat?  Before your move:  What am I trying to achieve?  Is my defence weakened?  Eventually you will be able to develop a mental list that becomes second nature.