Some cosmetic companies promise the moon: that their products will retard the aging process or that their computer will analyze skin problems over the department store counter.

But promises will not relieve or protect you from dry skin. Careful skin maintenance will. Dry skin, according to dermatologists Dr. Zenona W. Mally and Dr. Thomas P. Nigra, is caused by lack of water, not oil. When skin loses essential moisture from dry heat, wind and sunlight, your assorted lotions, oils and creams cannot restore the lost moisture unless they are used properly. Nigra and Mally recommend a bathing routine that does not include hot water, and encourage the use of lukewarm water. After bathing, applying a moisturizer within 20 minutes is the "essence of dry skin care during the winter months," emphasizes Nigra. "If you have very dry skin, then it is necessary to apply a heavy, greasy skin cream daily for three weeks if you are going to see any improvement. The creams prevent evaporation. Aquaphor is an old product that works well. Then you can switch back to a lotion." The newer lotions, Moisturel or U-Lactin, are recommended because they have increased oil content but do not feel greasy.

Sunlight is damaging to the skin. Mally believes that using a sunblock should become a part of the daily morning routine. "To have good skin you need good genes to begin. If you could avoid sunlight from the day you were born and extremes in environmental temperature, you could have very nice skin." Children should be taught to use sunblocks early.

Protection and preservation are the keys to good skin. Can computers help? "Hogwash!" says one dermatologist.