9 Under your fingernails
With the popularity of gel manicures, fingers and toes are now in the hot seat—literally, thanks to the UV lights used to seal the gel coat. You hopefully already know how damaging tanning beds can be to your skin, says Stephen Stahr, MD, of The Dermatology Associates of San Antonio in Texas, and those quick-dry devices are basically mini tanning beds for your nails. While you can’t get skin cancer on your nails, the damage can penetrate through the nail to the skin underneath. To make sure you’re safe, he recommends putting sunscreen everywhere, including on the tips of your fingers and toes. In addition, take a moment to examine your nail beds without polish on a regular basis because this black mark on your nail could mean you have skin cancer.