Since tennis elbow is almost always caused by repetitive motion, the important thing to do is to stop doing the activity that is causing the pain.
If stopping the activity isn't an option because of the type of work that you do, you should consult your doctor. These are some treatments that may help:
Massage: to relieve the stress and tension in your arm.
Heat: may relax and relieve pain.
Medications: your doctor may recommend an anti-inflammatory, such as ibuprofen, or an injection of steroids directly into the area.
Bracing: a brace can help minimize the movements causing the pain.
Surgery: an option in severe cases.
To prevent recurrence of tennis elbow, you can:
Exercise your arm: to build up strength and muscle.
Warm up: stretch your arms before participating in the activity.