Preventive skin care for teenagers needs to include no more than a daily routine of mild cleansing, moisturizing and sun protection - plus regular shampooing for oily hair, says Dr. Ellen Gendler, a dermatologist.

"The single most important criterion of any skin care routine is that it neither aggravate an existing acne problem nor bring on breakouts where there were none before," says Gendler, a member of the board of the Oil of Olay Skin Care Center.Wash your skin morning and evening with a cleanser designed to provide a rich lather without drying. Limit exfoliants or scrubs to twice a month since they can be irritating to acne-prone skin. For oily skin, use a mild, low-alcohol toner. If you are using acne medication, however, a toner can aggravate your skin. For dry skin, apply a greaseless moisturizer that won't clog pores. And use a sun block of at least SPF 15.

"Although most people are aware of the danger of prolonged exposure to the sun, few realize that the greatest damage comes from exposure before the age of 20," says Gendler.

She says girls generally are more diligent than teen boys about skin and hair care, but boys must fall into a routine, too. As they experience a burst of testosterone, they have a greater tendency than girls for breakouts on the chest, back and face, and shaving often increases the flare-ups.