11. Fall Short on Sleep
More than a quarter of Americans aren't getting the seven to nine hours of sleep we need nightly, and our skin (and bags under our eyes) show it.
"Your skin rejuvenates while you're sleeping," Dover says. He warns that a lack of sleep makes your face look "dull and listless" and can exaggerate the appearance of dark circles.
12. Ignore Warning Signs
A changing mole is one of the clearest signs of skin cancer. Spotting it early gives your doctor a chance to treat it before it has time to spread. But how will you ever know a mole is changing if you never look at your skin?
Check your skin from top to bottom, front to back in a full-length mirror once a month. "You're looking for changes in the size, shape, and color of moles or for new moles," Dover says. If you spot anything, or if you've got a personal or family history of skin cancer, ask your dermatologist to do a full exam as well.