The body's largest organ -- the skin -- is fast becoming the most vulnerable. According to the National Cancer Institute rates of the most deadly type of skin cancer, melanoma, have doubled in the past 30 years. The NCI estimates that 40 percent to 50 percent of Americans will develop one of the less lethal forms of the disease by the time they reach 65. Protecting yourself from overexposure to the sun is essential for staving off skin cancer in all its forms. But you can also set up your body to help prevent it.

Sun-protection basics bear repeating. Whether you're at the beach or going about your workday, wear sunscreen. Be especially vigilant when you're outside during peak hours, between 10 a.m. and 4 p.m. And don't count on your clothes to protect you. "If you can see right through the clothing, the UV rays can go right through, too," says Dr. Martin Weinstock, professor of dermatology and community health at Brown University.

If you're wearing something lightweight, apply sunscreen under your clothes. If you've never had a skin cancer screening, schedule one with your doctor or dermatologist. After that, the exam should be part of your routine annual physical. Screen your body monthly, too, using a hand mirror. Cancers can appear anywhere, even between your toes. Look for new markings or changes in the size, shape, color, or texture of existing freckles or moles-and tell your health-care provider about them immediately. Still, there's more to stopping skin cancer than just creams and screenings.