In a bathroom somewhere, a woman is stroking her jawline, hoping to remind her skin where it used to sit. Another is trying to follow the directions—in French—of a new facial-massage technique. And in that special place where desperation meets magical thinking, another is actually considering a face bra. When women confront the force that holds the moon in the earth's orbit, is it any wonder we fall for gimmicks and hype?

Skin sags when fat, collagen, and elastin break down. Still, "there is a lot we can control," says Fredric Brandt, a dermatologist in New York City and Coral Gables, Florida. Here, experts reveal the latest findings on the ingredients, nutrients, and daily habits that will help your skin stay firm.

1. Put spring in your skin. "If I had to pick one thing to fix in my skin, I would choose elastin," says Miami Beach dermatologist Leslie Baumann. "Elasticity is what makes youthful skin snap back when you press it." The sobering reality, though, is that we stop making elastin around the time we hit puberty. Using a cream or serum containing retinoids each day will help restimulate production.

2. Make collagen. Without collagen, skin is destined to have the same texture as an old leather bag. Fortunately, there's a way to make more: retinoids (again). They are the rare family of ingredients that dermatologists agree actually work. "We know that they stimulate collagen production and cellular regeneration," says Brandt. The nonprescription form, called retinol, can start working in six months. Prescription retinoids are more powerful but also more irritating.

3. Look out for your eyes. They should be the windows to your soul—not to your birth certificate. Big sunglasses help. Baumann also says to apply a retinoid at night.

4. Take cover. Sure, you could hide out in a cave. But it's a lot easier to simply apply sunscreen every morning, just as you know you should. The sun really is skin's worst enemy: "Long-term exposure causes collagen to break down and elastin to degrade," says Brandt. Choose broad-spectrum formulations with Helioplex or Mexoryl, which offer the longest-lasting protection, and be sure the SPF is at least 30.

5. Fight free radicals. Antioxidants are the superheroes of skin care. They protect skin from all the evil forces in the environment—also known as free radicals—plus block an enzyme called elastase that breaks down elastin. Choose products containing several different antioxidants—"they often work best in synergy," says New York City dermatologist Howard Sobel, who recommends those with vitamins A and C and coenzyme Q10.

6. Make the most of moisturizer. Here's one thing we bet you didn't know about moisturizers: They protect skin against free-radical damage. "Dehydration leads to oxidative stress, which generates free radicals," says Brandt. "Without moisture, your skin isn't able to repair itself and suffers even more damage." You just have to use the right product. Cholesterol, ceramides, essential fatty acids, and niacinamide are among the best ingredients—they improve skin's protective moisture barrier.

7. Relax your neck. During a workout, it's perfectly acceptable to sweat, pant, and even grunt—just don't strain your neck. "I see women do this when they jog," says Brandt. "They're strengthening the muscles that eventually pull down their faces."

8. Don't smoke. Rather than nag you to quit, we are just going to present the facts: "Smoking destroys collagen and elastin," says Brandt, "and it decreases levels of estrogen, which is necessary to keep skin firm."

9. Eat skinny foods. It's well known that food can make you thin or fat, alert or tired, happy or sad. Now add younger or older to that list. "New research tells us that low levels of vitamin C and zinc, among other skin-essential nutrients, may inhibit the skin's ability to repair itself," says New York City dermatologist Macrene Alexiades-Armenakas. To keep skin happy, eat more fatty fish (such as salmon), dark green vegetables (broccoli), almonds, and walnuts. And drink lots of green tea.

10. Ignore your cravings. It's not much fun to hear, but some experts believe that overindulging in sugar (and corn syrup, dextrose, and fruit-juice concentrate) can prematurely age skin—as early as our mid-30s. Sugar in the bloodstream forms harmful molecules called advanced glycation end products (or, appropriately enough, AGEs). And AGEs weaken collagen and elastin.