Different methods work for different types of stress. Relationship stress can be dealt with by stepping up and expressing your true feelings, tell your partner why you are stressed. Work stress can be dealt with a lot of sleep, and doing things you enjoy when work is over. School stress can be handled by determining yourself that you will do better. I can't give you an exact answer unless you can tell me what's causing your stress.
Meditation works for me. You find a quiet environment where you won't be disturbed. Turn off the phone, the TV, radio, etc., and play a tape or CD with a guided meditation. A CD that I like is called "Anxiety Relief," by Martin L. Rossman, M.D. I'm pretty sure I got it from Amazon. It relaxes the body, calms the mind, helps you to manage fear and worry and helps you to cultivate positive energy.