A foundation that's too thick will settle into fine lines and sap the luminosity from your skin. "Only use foundation where you need it to even out discoloration," says makeup artist Frances Hathaway. "You don't have to cover every inch of your skin." When buying a foundation, avoid those described as "matte," "velvet," and "long-wearing"; look for sheer liquid formulas with light-diffusing pigments. (A great option: Chanel Vitalumiere, $55; chanel.com.) If you have dry skin, foundation can look patchy and accentuate discoloration, so exfoliate two to three times a week and always apply a moisturizer after cleansing. Hathaway's favorite moisturizers to use under foundation: Aveda All Sensitive Moisturizer for combination or normal skin ($33; aveda.com) and Weleda Skin Food for dry skin ($18.50; usa.weleda.com).
Mistake #2: Over-Concealing Your Under-Eye Circles
A thick concealer that comes in a stick or pot will eradicate the shadows under your eyes, but it will also draw attention to the crepiness and fine lines that usually show up in that area first (because the skin there is thin). A better option: A brush-on highlighter pen (like Neutrogena Healthy Skin Brightening Eye Perfector, $11.99; drugstores) that uses illuminating particles, not opaque color, to camouflage dark circles. Apply it only near the inner corners of your under-eye area, where shadows are most prominent (and lines least).
Mistake #3: Wearing Deep, Dark Lip Colors
A dark color makes any surface look smaller--a welcome illusion perhaps on your hips but not your lips. To make your mouth look fuller (one hallmark of a youthful face), choose bright lipsticks and glosses (peaches, pinks, vibrant reds) over deep shades (burgundies, wines, browns). Makeup artists use another trick to create the illusion of luscious lips: Before applying color, trace a highlighter pencil along your upper lip line, then buff it out with your finger. (Try Nars Soft Touch Shadow Pencil in Hollywoodland, $24; narscosmetics.com.)
Mistake #4: Finishing with Powder
Youthful skin reflects light. Powders prevent light reflection and tend to magnify lines in the skin. If powder has been the final step of your makeup routine since high school, it can be difficult to quit cold-turkey. Here's a three-step program: First, switch to a very sheer translucent powder (like Laura Mercier Loose Setting Powder, $35; lauramercier.com). Then, start using it only on your nose and chin. Finally, trade the powder for a packet of blotting tissues--use one, only on the T-zone (nose, chin, and forehead), if you're shiny midday.
Mistake #5: Wearing Black Eyeliner
Don't skip eyeliner altogether--it's a great way to make your eyes look more open--but choose brown over black, which can be harsh. And keep the color diffuse. "You want to define the eyes with softness and blending, not strict lines," says makeup artist Troy Surratt. "A thick liner can leave the upper lids looking heavier than they are." The best technique: Trace a brown pencil liner along the upper lash line (into the roots of the lashes), focusing on the outer corners; smudge it with a Q-tip.
Mistake #6: Going Overboard with Lip Liner
A lip liner can define your lips and prevent color from feathering into any lines around the mouth--but choose one very carefully. If you line your lips too heavily, or with a color that's too dark, they'll look tight and pursed. For the most natural effect, your lip liner should match the color of your lips, not the color of your lipstick. Choose a creamy formula that won't adhere to any dry patches, and use it to fill in your lips entirely, so it wears evenly.
Mistake #7: Using Liner and Mascara on Your Lower Lashes
Playing up your lower lashes can make your eyes look droopy and draw attention to dark circles. Instead, curl your upper lashes and wiggle a volumizing mascara into their roots and slowly through the ends for the most uplifting effect. (Try Rimmel ScandalEyes Curve Alert Mascara, $6.99; drugstores.)
Mistake #8: Skipping Blush
A rosy flush on your cheeks brings instant life to your face. And, if applied correctly, blush can offer a little lift. Smile, find the fleshiest part of your cheek and apply color just slightly above it. Blend the color out toward your temples in circles, not a line, using a big fluffy brush. You want to avoid a stripe of color that stretches along your cheekbones, which can make you look drawn and hollow, says Surratt.
Mistake #9: Applying Lipstick Straight from the Tube
The borders of the lips soften with age, and any extra lipstick migrates easily. To avoid bleeding color, use your finger or a lip brush so that you don't deposit too much pigment. Concentrate the lipstick in the center of your mouth, and blend it out with a finger. Top it with a moisturizing balm or light gloss.
Mistake #10: Choosing a Too-Dark Eyebrow Pencil
"Your brow color fades as you age, so the brow pencil that you were using at 25 will look too stark against your complexion at 50," says makeup artist Denise Markey. She recommends Maybelline Define-a-Brow Eyebrow Pencils ($6.95; drugstores), which come in four shades. Choose the one that's a shade or two lighter than your natural brow color. If your brows are starting to get a little wiry, run a clear brow gel over them as well, brushing them up and out toward your temples.