Do pick lotions or creams. "When you use a spray or powder sunscreen, you're more likely to inhale chemicals," says Leeann Brown from the EWG. "It's great on your skin, but not in your lungs." Plus, it's easy to miss spots with sprays and powders.
Do look for a broad-spectrum sunscreen with zinc oxide, titanium oxide or avobenzone to help ward off damaging UVA and UVB rays.
Don't use a sunscreen that contains oxybenzone or vitamin A (sometimes listed as retinyl palmitate). Oxybenzone is a hormone disrupter that can penetrate skin easily; it's also a common allergen. Research suggests that vitamin A or retinyl palmitate might make skin more sun-sensitive and speed tumor growth. The girls at Natures Knockout also suggest the product should have at least 7% zinc/titanium dioxide.
Do slather--and repeat. Use about an ounce of sunscreen (enough to fill a shot glass) all over your body and reapply every two hours. Slap it on more often if you're swimming or sweating.