1. Wear sunscreen—and not just at the beach.
Rain or shine, "liberally applying a broad-spectrum sunscreen that contains both UVA and UVB protection every day is the single most important thing you can do to prevent sun damage and skin cancer," says New York City dermatologist Doris Day. We love Neutrogena Pure & Free Liquid Sunblock SPF 50 (for normal skin), Kate Somerville Protect SPF 55 Serum Sunscreen (for oily skin), and Clarins UV Plus HP Day Screen SPF 40 (for sensitive skin).
2. Quit smoking.
In addition to causing cancer and bad breath, smoking cigarettes "destroys collagen and elastin and decreases levels of estrogen, which is necessary to keep skin firm," says New York City dermatologist Fredric Brandt.
3. Use a retinoid.
It's the best way to slow down the clock with a cream. "Retinoids minimize the appearance of existing age spots and fine lines and prevent new ones from forming," says New York City dermatologist Heidi Waldorf. Try Dermadoctor Poetry in Lotion Intensive Retinol.
4. Stay hydrated.
No, Diet Coke doesn't count. "The more hydrated your skin, the better your wrinkles will look," says Montclair, New Jersey, dermatologist Jeanine Downie. "Drink lots of water, cut back on coffee and soda, and moisturize regularly." Try L'Oréal Paris Youth Code Day/Night Cream (for normal to dry skin) or Philosophy On a Clear Day Oil-Free Moisturizer (for oily skin).
5. Sleep well.
The expression "beauty rest" actually has some science behind it. "Not only does your skin require downtime to repair itself, but sagging skin and puffiness around the eyes make wrinkles look much worse," says Great Neck, New York, dermatologist Jeanette Graf.
6. Maintain a healthy weight.
Not surprisingly, yo-yo dieting isn't great for your skin. "Skin loses elasticity over time," Waldorf says. "The more your weight fluctuates, the harder it is to snap back into shape."
7. Eat right.
"Your skin receives nutrients not only from creams and treatments, but also from the food you eat," Waldorf says. "The more balanced your diet, the younger you'll look. And if you're not taking a multivitamin, start now." To keep skin happy, eat more fatty fish (such as salmon), dark green vegetables (like broccoli and spinach), almonds, and walnuts. Drink lots of antioxidant green tea. And lay off the refined sugar and booze—both cause aging inflammatory reactions in the skin.
8. Get moving.
"Exercise increases blood flow to the skin and promotes a glowing, healthy-looking complexion," Downie says. "Working out for just 30 minutes four or five days a week can make a huge difference."
9. Try to relax.
The mind-body connection is a powerful one. "Do whatever you need to do to decompress," Waldorf says. "Stress causes cells to age faster, which absolutely shows on the skin."
10. Don't pick.
You got the same advice when you were a teenager. "Sun damage causes dark spots as you age, but so does picking at your blemishes," Waldorf says. "And since the skin takes a lot longer to repair itself as you age, the spots won't disappear right away." To clear up an outbreak, try La Roche-Posay Effaclar Duo, which contains benzoyl peroxide to kill acne-causing bacteria, and lipo-hydroxy-acid to help keep pores clear. If—against doctors' advice—you did pop that zit, use Clean & Clear Advantage Popped Pimple Relief Drying Paste, an overnight treatment that will help it heal.