There is no longer one-size-fits-all moisturizer, and the thought of plain old soap touching already-dry skin sends chills down the silky smooth backs of dermatologists and product-development executives.

The change in attitude - and in offerings from cosmetic companies - has been fueled by technology, consumer demand and smart marketing, says Lydia Evans, a Chappaqua, N.Y., dermatologist and consultant for L'Oreal.

"People are much more aware about their skin than they used to be. At least they're aware of changes, if not the actual problems," Dr. Evans observes.

Both women and men have come to realize that "skin care" means taking care of skin, she says.

"Skin is a changing biological organ. It affects appearance, but it also is a major defense organ. It's the first line of defense against environmental elements."

As for the simple aesthetics, covering up the signs of aging is really "old school" now that technology has discovered ways to combat them, adds Angela Gibbs, product manager of Lubriderm's anti-wrinkle Skin Renewal line.

It's time to change or at least start a new skin-care routine when the skin feels drier, becomes more sensitive to weather or products or lines begin to appear.

"You see your skin every day, but do you really look at? ... give it an annual checkup," Ms. Gibbs says.

She also urges people to pay attention to the skin all over their bodies, particularly areas, such as the hands, that are repeatedly exposed to the sun.

One test: Pinch the skin on the back of the hand. If it doesn't go back to the original shape right away, it's a sign that the skin is losing its elasticity and needs more attention.

Routines should be re-evaluated about once every 10 years to match hormonal, environmental and lifestyle changes.

But taking on a new skin-care regimen - even one that promises to reduce the appearance of fine lines and rebuild collagen fibers - doesn't produce overnight results, Dr. Evans says. So people often become frustrated and quit before giving the products a chance to work.

Others stop using the products almost as quickly as they start because the active ingredients, particularly alpha and beta hydroxy acids and retinols, can initially irritate skin.

Dr. Evans recommends that people looking to begin an anti-aging skin regimen begin with one of the hydroxys, which exfoliates and stimulates collagen fibers. These are targeted to people in their late 20s and early 30s who notice little lines around the eyes.

Collagen, which Dr. Evans calls "the bricks of the house," really begin to break down when most people hit 40. Retinols, derivatives of vitamin A that are most commonly used in products for mature skin, will help reverse this, she says.

"It is well documented that retinols continually build up collagen bundles - the one part of the body you want plump."

Retinols are the strongest ingredient used in skin products, but with their increased effectiveness comes a tendency for irritation.

Using these ingredients on a graduated cycle may help, Dr. Evans notes, because it is possible to build a tolerance to some of the aggravating factors.

Lubriderm's Skin Renewal uses a poly hydroxy acid, which is said to be gentler.

Poly hydroxy acids are larger cells and penetrate more slowly than alpha hydroxys but still have anti-aging and moisturizing properties, explains Susan Wendling, director of product development at Lubriderm. And the antioxidants in the formula help protect the skin from environmental damage.

Sun, of course, is the biggest enemy of the skin and the aging process, Dr. Evans and the Lubriderm team agree. They urge daily use of moisturizer with sun protection or a separate sunscreen.

And Dr. Evans explains that dark circles under the eyes can come from repeatedly rubbing the area. (She say people rub their eyes much more often than they think - when they're tired, when their allergies are acting up and out of habit.)

When the skin under the eye is thin, light penetrates it. To combat dark eyes, Dr. Evans suggests using eye-specific moisturizers, which typically aren't as thick, which also diffuses light.

Skin-care routines should be built around the appropriate moisturizer, Dr. Evans says, but cleanser is an important element. Cleansers are kinder to skin than bar soap because they do the same job but don't strip away natural oils in the process.

"You want to be clean but not squeaky clean," she adds.