Another layer of sun protection is clothing. For small babies, light, loose cotton clothing is ideal. You want coverage, but you also don't want them to overheat. For older babies, let swimsuits, trunks or swim shirts do double-duty -- you can buy them with added SPF. The ideal, says Dr. Jeff Ashley, is a rash-guard like top and bottoms with good coverage for boys or girls. The more coverage, the better, he says: “That way, there’s less skin that needs sunscreen."