6. Hydrate your skin from the inside out.
"It's not possible to have good skin if you don't drink enough water," says Mary Lupo, M.D., associate clinical professor of dermatology at Tulane University School of Medicine in New Orleans, who downs a minimum of six glasses a day. "When you're dehydrated, your skin is one of the first organs to show it."
7. Waste not, age not.
"After applying sunscreen to my face, I rub whatever is left on my hands onto my neck and chest, two areas people always forget," says Lewis, who uses sunscreen with an SPF of at least 15 every day. (You can also do the same thing with anti-aging creams.) Dermatologist-recommended sunscreens include Avon Skin-So-Soft Moisturizing Suncare Plus SPF 30 ($12; avon.com) and SkinCeuticals Ultimate UV Defense Sport SPF 45 ($34; skinceuticals.com).
8. Give skin below the neck its due.
"We often neglect the skin on our bodies," says Evans, who makes sure to give herself an in-shower sloughing with a body scrub (which can get rid of dead skin cells and make skin smooth) every other day. "You would have to use a washcloth very harshly to get the same results you get from the fine granules of a good scrub," she adds. (Try Clarins Exfoliating Body Scrub, $28; gloss.com, or Aveda Smoothing Body Polish, $18; aveda.com .)
9. Feed the skin with exercise.
"Exercise boosts circulation and keeps oxygen and nutrients flowing to the skin, giving it a fresh, radiant look," says 35-year-old bicoastal dermatologist Karyn Grossman, M.D., who never misses her 6:30 a.m. run -- either outdoors in Santa Monica or in the gym when she's in New York City. She's also an avid hiker and loves to sail and scuba dive. Lewis takes a more low-key tack to fitness: three one-hour sessions of Iyengar yoga every week at her local gym.
10. Don't let skin go up in smoke.
"I don't just not smoke, I avoid smokers and smoky situations at all costs," Lupo says. "When I make a reservation at a restaurant and they ask, 'Smoking or non?' my reply is, 'Not even close.'" Smoking constricts the capillaries, depriving the skin of much-needed oxygen, Lupo explains.
11. Always apply moisturizer after washing hands.
Dry, indoor air, cold weather and frequent washing can suck the moisture out of the skin on your hands. Grossman knows from personal experience; she estimates that she washes her hands at least 30 times a day. Grossman's favorite: Aquaphor Healing Ointment ($8; at drugstores). Others to try: Vaseline Intensive Care Renew & Protect Lotion ($2; at drugstores) or Dr. Hunter's Rosewater & Glycerine Hand Creme ($10; caswellmassey.com).