Runescape has a pretty list of rules that might help you. Its called the Responsible Gaming Policy.
Take a break from the computer; read a book, watch a movie.
Exercise at least once a week.
Remember it is just a game.
When eating, take a break from the computer - it'll still be there when you come back.
Don't ignore your real life friends, meet up with them on a regular basis.
Work, or study matters; don't let playing a game stop you doing well in your studies or at work.
