You can bet Demi Moore's flawless face is a result of priming before makeup.

For aging skin, silicone is “one of the best things ever added to cosmetics and creams,” says Heidi Waldorf, M.D., 42. “Products go on silky, stay smooth, and seal in moisture”—an ideal anti-aging skin care tip for complexions that are parched or crepey.

She dabs Olay Regenerist Daily Regenerating Serum under her eyes before applying makeup. “With its high concentration of silicone, it acts like a primer, filling in little creases.” Look for dimethicone or cyclopentasiloxane on labels.