Caring for your cosmetics isn't difficult. Here's what you need to know:

Anything with liquid should be thrown out after a year. Mascara -- which breeds bacteria -- should be trashed every three months. "Anything you've had more than two years is really silly," says Paula Begoun, author of "Don't Go to the Cosmetics Counter Without Me." "Many people don't even keep computers that long."

Makeup should be kept at room temperature. Not in places such as the car or the bathroom, where high temperatures can cause the emulsification to break down. And never in the refrigerator.

With the exception of using acetone to thin old nail polish (one of the few beauty products that really can last forever, experts say), don't add water or anything else to makeup or moisturizers to loosen it up.

Because they pick up dirt and oil from your face, brushes breed bacteria. Clean them once a month. "You don't have to buy a special brush cleanser," says Begoun, who runs the Web site www.cosmeticscop.com. Instead, she says, try a mild shampoo such as baby shampoo.

The plastic film between your powder compact and the puff is there for a reason. "It's there to keep the puff -- which touches your face and picks up oil -- from touching the powder," says Wendi Wilson of Potion, a cosmetics store in Charlotte. Separating the puff from the compact will keep your powder from getting a hardened layer on top, she says.