If new wrinkles and sun spots seem to appear overnight, chalk it up to cumulative sun exposure and waning estrogen levels, which affect skin's firmness, elasticity, and moisture, says Lance Brown, a clinical assistant professor of dermatology at New York University School of Medicine. Although you can't undo the past, you can combat further damage and reduce your risk of skin cancer. Apply a moisturizer and a broad-spectrum sunscreen with SPF 30 or higher under your makeup daily, even on cloudy days, says Brown. Choose a sunscreen thatcontains zinc or titanium and avoid any with oxybenzone, which can cause allergic skin reactions and potentially disrupt hormones.