Fail to use sunscreen every day. Sun exposure without protection is the most damaging thing you can do to your skin. Use a sunscreen of at least 30 SPF on your skin every day. My protocol for when and how often to apply appears below. Remember to wear sunglasses when you are outdoors. Squinting can cause crow’s feet and frown lines, not to mention damage to your vision. Here are some additional tips to remember:

Fail to use sunscreen every day

• Limit your time outdoors when the sun is at its peak between 10:00 a.m. and 3:00 p.m.

• Give your skin time to absorb sunscreen before sun exposure. Apply sunscreen liberally, fifteen minutes to half an hour before going outdoors.

• Use enough sunscreen to coat all skin that will not be covered by clothing. Most people apply only 25 to 50 percent of the recommended amount. Follow the guideline of “one ounce, enough to fill a shot glass” to cover the exposed areas of your body.

• Do not forget your lips. Use a product that has been specially formulated for your lips with an SPF of 20 or more.

• Wear long pants, a shirt with long sleeves, and a hat with a wide brim if you are planning to be out during peak hours. The lighter the color and more tightly woven your clothes, the more protection from the sun they will afford. A white T-shirt has an SPF of only 5. You can buy clothing with built-in SPF or wash the clothing you wear outdoors with a laundry aid like SunGuard, which gives clothes a higher SPF.

• Reapply sunscreen frequently, every two or three hours, depending on the time of day and what you are doing. Be sure to use a generous amount each time. A thin coat of protection can reduce the effectiveness by as much as 50 percent. Remember to protect your ears and hairline.

• Be careful about reflected light. A beach umbrella or shade trees give you only moderate protection. UV rays reflect from sand, snow, and concrete. They even penetrate water. The underpart of your chin is particularly vulnerable to reflected light. You do not want to contribute to signs of aging on your neck if you can prevent it.

• There is no such thing as a healthy tan. If a burnished look appeals to you anyway, take it slowly and let the skin build up melanin gradually. Do not use tanning beds. Tanning beds and sunlamps generally emit 93 to 99 percent UVA radiation. This is three times the UVA radiation given off by the sun.

• Be aware that some medications increase the risk of UV ray damage. Check with your doctor about the medications you are taking and any new ones that might be prescribed.

• Know that some skin types are at a greater risk of UV damage.