Adequate protection against UV radiation is the best way to avoid skin cancer and prevent premature aging.  Brief exposure to sun on a regular basis is a good source of Vitamin D and has important psychological benefits, but the skin must be fully protected against harmful UVA (aging) and UVB (burning) rays.  These are the basics of sun protection:

1) Sunscreen.  Use an SPF of 15 or higher, and apply it 30 minutes before sun exposure, then every few hours thereafter. Reapply immediately after swimming and sweating.  Note that winter sun is no less harmful than summer sun, so the same rigorous application of sunscreen goes for skiing or any sport or exposure at any time of year.

2) Sunglasses.  Buy total UV protection eyewear.

3) Clothes and Hats.  Covering should be used in addition to sunscreen.

4) Avoid Peak Hours.  Be extra-diligent about protection between 10AM and 4PM, when UVR is strongest.

5)  Learn to take note of the daily UV Index.  This is particularly relevant now that scientists overwhelmingly agree on global climate change.  The Ultraviolet (UV) Index was developed by the National Weather Service (NWS) and the Environmental Protection Agency (EPA) to provide a forecast for the amount of ultraviolet light expected to reach the Earth's surface on a given day. The higher the index, the faster UV radiation causes damage to the skin and eyes.  The Index predicts UV levels on a scale of 0 to 10 and is published in daily newspapers or included in TV/radio weather reports.  Take extra precautions to protect your skin when the Index is high (above 5).