Urinate before and soon after intercourse. Urinate as soon as you feel the need to, and try to empty your bladder completely. Drink plenty of water. Aim for eight glasses of fluids per day. Drink fruit juices containing vitamin C. Vitamin C seems to help prevent bacterial growth.
Some women believe cranberry juice is especially helpful.
Avoid deodorant soaps and sprays. Use tampons as seldom as possible, and change them frequently when you do use them. Don't use deodorant sanitary napkins. If you use a diaphragm for birth control, check with your doctor. You may need a different diaphragm, or even a different birth-control method.