If diamonds are a girl's best friend, then lipstick is her soul mate. Even with flawless makeup, most women don't feel complete until their lips are lined, glossed or otherwise coated in color. To get the sexiest lips possible, follow these eight simple steps.

1. Exfoliate. To keep the skin on your lips smooth and make lipstick glide on more evenly, regular exfoliation is key. One easy, at-home method: Aloette Soothe n' Smooth ($24.50; aloette.com), a two-part scrub-and-balm set designed to remove flakes and nourish lips with peppermint, beeswax, aloe and safflower oil. Editors' trick: Take a clean, dry toothbrush (not the one you use to brush your teeth) and rub a bit of Vaseline onto the bristles, then gently brush your lips for several seconds to smooth away rough spots.

2. Condition with balm. Without moisturization, getting the perfect pout is virtually impossible. "You really have to be a lip-conditioner junkie," says Gordon Espinet, global makeup artist for M.A.C Cosmetics. That's why you should slather on a lip balm full of moisturizing emollients like beeswax or glycerin, as well as good-for-you vitamins like the antioxidants C and E. Try Neutrogena Overnight Lip Treatment ($3.49; at drugstores) with hydrating vitamin E and glycerin. Or look for superhydrating sheer glosses that add a touch of color too. We like aveda lip shine ($13.50; aveda.com), rich in conditioning botanicals like plant lipids.

3. Alternate lipsticks from time to time. While matte shades tend to have more pigment and fewer moisturizing ingredients (that's what makes them last longer), most nonmatte lipsticks actually help your lips retain moisture, according to Ronald Moy, M.D., president of the American Society for Dermatologic Surgery. A better bet: Revlon Moisturous Lip-color ($7.50; at drugstores), which comes in 24 shades.

4. Treat the first signs of aging. One of the most common complaints: those annoying lip lines that develop with age and trap lipstick. Daily prevention is key: It will pay off in the long run by lessening the deeper lines and wrinkles that are much harder to get rid of completely. Retinols are effective in the war against wrinkles, specifically prescription anti-aging creams like Avage, Tazorac and Retin-A, Moy explains. Editors' trick: Try wearing a lipstick with retinol like beComing Lip Delux Smoothing Retinol Lipcolor ($12; www.becoming.com).

5. Use the right liner technique. How to do it correctly: Start with a liner just slightly darker than your lipstick shade and outline the shape you desire (going outside your lip line slightly will make lips look fuller). Next, use the side edge of the liner tip or a lip brush to feather the color inward. Then, fill in with the lighter lipstick. For easy application, choose a pencil in a nearly nude shade, such as Bliss lip liner stick in Pink Eraser ($15; blissworld.com).

6. Protect lips from the sun. Because lips have a minimal amount of melanin, they have no natural defense against the sun, says Dennis Gross, M.D., a New York City dermatologist and the founder of the M.D. Skincare line. Gross' advice: Always apply an SPF 15 lip balm under lipstick and reapply frequently during the day. For effective coverage, try the all-natural aveda lip saver ($7.50; aveda.com) with SPF 15.

7. Adopt good habits. Major lip mistakes can result from bad habits; smoking, for example, aside from damaging your health overall, speeds up the formation of vertical lines around your mouth. Licking your lips also can make them rough and prone to chapping (your saliva evaporates and pulls away even more moisture from your lips in the process). Also, no matter how nervous you are, don't bite your lips. The skin there lacks an outer layer of protection that body skin has, so it can easily be broken, making it prone to infection.

8. Use the right shade of lipstick. Just because a particular color is the current rage doesn't mean it will work for you. Test a new shade on your lips, not just on the back of your hand: "You might as well just be looking at it in the tube, because it's not going to be the same on your face," explains Jennifer Artur, a makeup artist and owner of A Beautiful Life beauty boutique in New Hope, Pa. When in doubt, go with a beige-pink color (or beige-brown color if you have darker skin). One neutral color that works well on just about everyone: Maybelline Wet Shine Diamonds lipstick in Pink Topaz ($6.75; at drugstores).