Of all the skin sins, going out unprotected is the worst. UV rays cause 90 percent of wrinkles, sun spots and other signs of aging. And although face lotions with sunscreen ward off burning UVB rays, not all fully shield you from UVA, the deeply penetrating light that ages skin. What to look for: If your skin is sensitive, zinc oxide or titanium dioxide are natural minerals with stellar UVA coverage; otherwise, you may want the longer-lasting protection of chemical-based SPF with UVA-blocking avobenzone or octocrylene.