YOU'RE SCARED OF RETINOIDS
Though they once held a reputation as an aggressive ingredient, derms say a pea-size amount rubbed all over your face helps speed cell turnover—and today's formulations are gentle enough for sensitive skin. (If your skin is superfinicky, apply retinols every other night until your skin can better tolerate them.)
YOU DON'T PROTECT EVERY INCH
Make sure to rub two teaspoon-size blobs of SPF 30 all over your face, neck, hands, and chest—but don't forget other oft-skipped spots: "In my practice, I'm seeing an epidemic of skin cancer along the hairline, the jawline, and the ears," says dermatologist Dennis Gross.
YOU DON'T KEEP UP WITH YOUR SKIN TYPE
Skin gets drier, thinner, and more sensitive as you age, which means the perfect moisturizer right now might not always be your go-to. Dry, oily, or combination may be the descriptors on skin-care packaging, but derms recommend thinking in terms of issues (redness, zits, wrinkles) instead.
YOU TREAT ADULT ACNE LIKE A TEEN ZIT
All pimples are not created equal—teen acne is often due to puberty and excess oil, while adult acne stems from stress, hormonal shifts, and increasingly delicate skin. To treat big-girl blemishes, use a moisturizing salicylic acid cleanser with ingredients like soy, and switch your 5 or 10 percent benzoyl peroxide treatment to one that contains just 2.5 percent. "Too much benzoyl peroxide can actually dry out a zit and stop medicine from penetrating," says Jeanette Graf, assistant clinical professor of dermatology at Mount Sinai School of Medicine in New York City
YOU USE PRODUCTS AT THE WRONG TIME
Get the most out of your skin-boosters by tweaking your schedule: Use antioxidants in the morning to protect your skin throughout the day, and exfoliants (like glycolic acid lotions) and collagen boosters (like retinoids) at night to shed and rebuild cells.
YOU PUT OFF ANTI-AGING TREATMENTS
Start anticipating changes so you can prevent deep lines before they start. If you spot a crinkly or crepey area of skin, start applying serums and lotions containing a mix of peptides ASAP. "Peptides give you the building blocks to make collagen," says Ranella Hirsch, clinical assistant professor of dermatology at Boston University School of Medicine.
YOU FOLLOW SKIN-CARE TRENDS
There are so many new, shiny toys on the skin-care market that it's easy to get swept up in the hype—but it's best to go with what you know (or, at least, what's been clinically proven). What's tried and true? Alpha hydroxy acids, retinoids, and peptides are great for fine lines and wrinkles. Salicylic acid works for acne, green tea calms redness, and vitamin K helps with dark undereye circles.