Your 20s and 30s continued...
Additionally, Fox says, you can start dipping into the anti-aging jar as early as your 30s.
"There is some evidence to show that anti-aging ingredients might have some preventive effects as well," says Fox, director of Advanced Dermatology and The Center for Laser and Cosmetic Surgery on Long Island.
What you can try now: Products containing alpha-hydroxy or beta-hydroxy acids, and microdermabrasion products including scrubs and skin polishers.
Makeup tips: Your 20s and 30s are the decades to let your natural beauty shine, says former Hollywood makeup artist Barbara Fazio. The biggest mistake women in this age group make: trying too many trends at once.
"These are still the years when women want to look trendy and modern, but too often they try too many trends all at the same time," says Fazio, now director of the B. Fazio salon in Lakewood, Ohio.
To stay on-trend but not overdone, she says, pick one item from a particular trend -- say, metallic eye shadow or glitzy lips -- and never wear more than one trend on your face at a time.
Even women who are the same age may have different skin needs. This is particularly true when you hit your 40s, since many problems that pop up during this decade hinge on what you did in your 20s and 30s.
"If you wore sunscreen, if you did some preventive care, then you may not notice any major difference in your skin," says Fox. "If you didn't do those things, then fine lines and wrinkles are definitely on the upswing once you hit 40."
The problem is a breakdown of collagen, natural fibers that form an invisible network of support underneath the skin and help it stay plump and firm.
As collagen stores begin to break down -- a process that is accelerated by sun exposure -- skin loses its moist, dewy look. In its place is drier, more fragile skin, with fine lines and small wrinkles appearing around the eyes and in the nose-to-mouth area.
Further, as the years pass, we shed old skin less frequently. That means your complexion looks not only drier, but also more dull and uneven.