Tanning beds. According to the Skin Cancer Foundation, "fake and bake" tanning emits up to 12 times more UVA rays than the sun. Tanning bed exposure in youth can increase melanoma risk by as much as 75 percent, and people who use tanning beds regularly are more likely to have other skin cancers, too. Keeping out of the sun, especially during the hours of 10 a.m. to 4 p.m., is the only surefire way to stay safe. Sunscreen with SPF delays the effects those UVB rays have on your skin, but the FDA hasn't established criteria for measuring protection against UVA rays. New labels do show ratings of UVA and UVB protection, so look for a sunscreen that scores high on both of these assessments to best protect your skin.