Sudoku

Many people are caught up in this Sudoku craze. I haven't caught the bug, yet, but I'm interested in the various descriptions of how to play. Some are better than others. Check out the following websites that offer rules and tips for playing Sudoku. How might you improve them?

http://www.sudoku.com/
http://www.puzzle.jp/letsplay/sudokuruleflash-e.html
http://www.sudoku.name/rules/en
http://www.cambridge-news.co.uk/lifestyle/games/home.lpf