I am not a crack player by any means, but can hold my own on the board. Thought I would offer some constructive ideas for the players out there.
1. Castle early in the game, it prolongs the life of your king.
2. Open the lines for your bishops, don't entrap them behind pawns and waste their long range powers.
3. Make every move serve a purpose. is it a check to the king or are you setting up a pin or attacking a high value piece such as a rook or queen? dont just move pieces for the sake of moving pieces.
Here are some of the books that have helped me along the journey to become a better player. It helps me to pull out a chess board and walk through the games in the books.
Beginner Books
The Tao of Chess, Peter Kurzdorfer
How to Win Chess Openings, I.A. Horowitz
Intermediate Level Books
How to Reassess Your Chess, Jeremy Silman
Art of Attack in Chess, Vladimir Vokovic
My secret trick for really boosting my game is the Chessmaster 9000 software. I play the computer with my opponent set to a rating of 2000+. Needless to say I get a good thrashing, but when I play Joe Sixpack its makes for some fireworks. Not sure that I can picture Joe Sixpack playing, but you get the picture.
http://www.chessmaster.com
If someone has a better system for improving play, let me know, I am all ears.