At the risk of sounding matronly...
Drink plenty of water and get a decent amount of sleep. If you are feverish, stay away from alcohol. You probably already knew that. And stay physically active. I believe it boosts the immune system. I hope you feel better for your IM soccer season.
Everyone else, feel better! If you have sick roommates, stay away from their cans of diet coke! Bad habit of sharing drinks with my sisters!
pbpck