Your No-Fail Plan: In Your 20s

Use gentle products, and focus on damage prevention. "You don't need antiwrinkle creams or microdermabrasion in your 20s," says Ranella Hirsch, MD, president-elect of the American Society of Cosmetic Dermatology & Aesthetic Surgery.

Cleanser: If you have normal skin, you need to wash it only before bed, says Lupo. Use a mild cleanser—either a gel, if your skin is oily, or a milky one, if it's dry.

Moisturizer: Pick a brand, any brand. But be absolutely sure that your moisturizer has SPF 15 or 20, and that it gives you both UVA and UVB protection. Apply it all over your face and on your neck and chest, says Lupo. (This is critical no matter what your age.)

Nighttime treatment: Use a hydrating fluid or an oil-free moisturizer. Many dermatologists recommend starting on the vitamin A-derivative prescription retinoids (like Retin-A, Tazorac, and Avage)—the gold standard for reducing fine lines, stimulating collagen, and treating acne—or products containing the less potent, over-the-counter retinol. Before bed, apply a pea-size amount all over your face and right up under your eyes, says Hirsch; then you don't need an eye cream.