Using the wrong type of sunscreen can further damage sun-exposed skin, a U.S. skin specialist warns.

New York dermatologist Dr. Bruce Robinson of the American Society for Dermatologic Surgery advises choosing products with zinc oxide that provide a physical block against the sun and do not take 20-30 minutes to become effective.

Read the sunscreen label and look for broad coverage that protects not only against ultraviolet B but also ultraviolet A that can pass through windows and penetrates more deeply into the skin, Robinson says.

Robinson advises to apply sunscreen evenly and often. He recommends applying a shot glass size amount of sunscreen to the entire body and a teaspoon of sunscreen to the face -- cautioning some bodies may require more than the recommended amount. Cover all body parts, even those not exposed to the sun, with a thin even layer of sunscreen and reapply every two hours, Robinson says.

"There are many ingredients and factors consumers should look for when choosing sunscreen products," Robinson says in a statement. "I tell my patients to avoid getting hung up on product gimmicks, and to instead pay more attention to the basics of sunscreen protection and their sunscreen regimen."