Remind your teen about the basics of protecting her skin from the sun. If she's in the sun, she should slather on at least two tablespoons of sunscreen at least every two hours. Encourage her to cover up with a wide-brimmed hat and sunglasses with ultraviolet (UV) light protection. And if she's prone to freckles, sunburns easily or has light-colored hair or eyes, urge her to keep sun exposure at a minimum and have a health care professional examine her skin regularly. Between visits, she should examine her own skin for signs of any mole that's changed size or shape.