10 Smart Ways to Lower Your Skin Cancer Risk

6. Remember when to apply -- and reapply -- sunscreen.

6. Remember when to apply -- and reapply -- sunscreen. "It takes 20 to 30 minutes for sunscreen to be properly absorbed by the skin -- and it won't be effective till it sinks in," explains Dr. Cordoro. So put on lotion half an hour before you leave the house. Blocks win in this category too: "They take effect almost immediately," says Dr. Cordoro.

Should a sun-protective lotion go over or under your makeup? If you're applying several skincare products, the general rule is that the first item you put on should be the sunscreen. And most cosmetics, as long as they're not too watery, won't affect the sunscreen underneath too much. "It will look better to have your foundation and powder on top," Dr. Weinkle points out. To help protect yourself and still look beautiful, choose cosmetics, moisturizers, and eye creams with a built-in SPF.

Just as important as getting it right before you walk out the door is making sure you're covered throughout the day. "Reapply every hour if you're doing anything more than moderate exercise -- even if your sunscreen is waterproof and regardless of the SPF," says Dr. Adams. Why? To be declared "waterproof," sun lotions usually only have to be tested on people doing things like lounging around the pool or spending time in a whirlpool, rather than on those who are running, biking, or swimming vigorously -- which means these products are not hard to wash or sweat off. And SPF is irrelevant if there's no sunscreen left on your skin! (By the way, waterproof products will generally stay on longer than anything labeled water-resistant.)