Know which SPF is best
SPF, or sun protection factor, is an indication of a sunscreen’s ability to screen out ultraviolet B (UVB) radiation and protect against sunburn. An SPF of 15, the minimum most dermatologists recommend, technically filters out about 93 percent of UVB radiation. An SPF of 30 filters out almost 97 percent. There are inadequate testing methodologies for evaluating SPFs above 30, so you can probably skip the higher numbers. Remember: No sunscreen is 100 percent protective against harmful radiation from the sun, so you’re getting some radiation even when wearing sunscreen.

Read the label
Choose a sunscreen that claims “broad-spectrum” or both UVB and UVA protection. UVA accounts for 95 percent of the UV radiation reaching the Earth’s surface. Recent research also shows UVA can more deeply penetrate the skin than UVB, is associated with wrinkling, and may inhibit DNA repair. Although there are no rating standards for levels of UVA protection, certain ingredients are known to be effective. Look for avobenzone (also called Parsol 1789 and butyl methoxydibenzoylmethane), which chemically absorbs radiation, and titanium dioxide and zinc oxide, physical blockers that reflect radiation.

Get oiled up before you go outside
Apply sunscreen generously to all exposed skin 20 to 30 minutes before sun exposure. Use about the amount that would fit in a shot glass to cover the hands, arms, face, neck, and ears.

Don’t forget to reapply
Ignore label terms such as “all-day protection.” In fact, no sunscreen is effective for more than about two hours. Even water-resistant sunscreens need to be reapplied every 40 minutes (80 minutes for “very water-resistant”) or after drying off with a towel.

Don’t skip your lips and eyes
Use lip protection with an SPF of 15 and one of the UVA-protective ingredients mentioned above. Only wear sunglasses that have 100 percent UV protection, and preferably ones that wrap around your face, which offer the best coverage.

Be aware of your daily meds
Certain topical skin medications and oral antibiotics and contraceptives can increase your sensitivity to the sun, making it that much more important to be cautious and be aware of your med’s side effects. Protect your kids Don’t use sunscreen on infants younger than 6 months; rather, keep them out of direct sunlight. Teach older children to wear sunscreen and hats and to be sun smart.