To cover up an imperfection -- say, a spider vein or tattoo -- you obviously want to match the shade of foundation to the skin tone of your body. Don't think you can just slap your everyday foundation over a bruise and call it a day. "If you wear a high SPF on your face daily, your neck and body may be darker, so a foundation that matches your face may not match your body's skin tone," says Sephora Pro Artist Helen Phillips.

Another reason your everyday foundation won't work? The formula is probably too lightweight to give you the coverage you need. And it won't have the staying power that body makeup has -- meaning it could end up all over your clothes.

Koury advises gently dabbing foundation directly over an imperfection and feathering outwards to blend into surrounding skin. You can use your fingers, but since you are working with heavy-duty formulas, it is best to use a brush. (I learned this the hard way and spent the night scrubbing foundation from my nail beds.) Look for a synthetic foundation or concealer brush to avoid obvious foundation lines, says Koury. If one layer doesn't cover it up entirely, let the foundation dry for three to four minutes, dust a setting powder over it and apply another layer. For the record, Victoria's Secret model Selita Ebanks once told the New York Daily News that, prior to going down the runway, her butt receives no fewer than 20 coats of makeup. Makes you feel a little differently about those perfectly shaped cheeks, now doesn't it?

When you reach your desired coverage, says Koury, finish with a generous amount of setting powder and wait two minutes before brushing off the excess. This gives the powder enough time to set on the skin and will help your makeup last longer. This is probably the most important step because that setting powder is the only thing standing between you and brown smudges all over your party dress.

If you follow these steps religiously, the makeup will last for days -- literally. On a recent weekend trip to Vegas, I applied makeup to cover up some particularly unflattering bruises on my legs and it lasted for two days (and yes, I showered). I even wore a beige skirt and it made it through the night mess-free.

"Covering tan lines is the same as concealing other body flaws -- only this time the discoloration is lighter versus darker," says Koury. Again, match the shade to the tanned area and then build the coverage over the lighter areas. Remember to set the foundation with a powder.

Sadly, no. Since cellulite is a texture issue, not a pigmentation issue, makeup can't cover it up. But there is a silver lining: "Since darker tones recede visually and look smaller, cellulite will look less noticeable on a 'tanned' or bronzed leg than one that is not," says Koury. You can do this by using applying body makeup that is a slightly darker shade than your skin tone. Just make sure to apply it all over your leg instead of in one concentrated area.