According to Dermatologists, the suns ultraviolet light is your skins biggest enemy - which means sunscreen may just be your skins biggest friend. All sunscreen products today block out burn-causing UVB rays; very few adequately block UVA rays. Yet, it is these long, glass-penetrating UVA rays that are responsible for the wrinkles, collagen and elastin breakdown, brown spots, and broken capillaries associated with sun damage. To help your skin, you need a product that is labeled "broad-spectrum," which means it blocks both types of rays. You also need a formula that boasts an SPF of at least 15; with the thinning ozone layer, cautious dermatologists suggest an SPF that is no lower than 30.

Chemical sunscreens

Chemical sunscreens use chemicals that absorb UVA and UVB light, preventing it from damaging surrounding skin cells. There are a lot of chemical ingredients currently used in sunscreen, but only Parsol 1789 blocks out both UVA and UVB effectively. Remember, it's important to block out both skin-ruining UVA and burn-causing UVB rays!

Don't use old sunscreen because these products lose their effectiveness after 1 to 2 years. If you can't find an expiration date and can't remember when you purchased your sunscreen, buy yourself a fresh bottle.

Physical sunscreens

Physical sunscreens are sometimes called sun-blocks because they form a barrier to block the entry of UVA and UVB light. Titanium dioxide, which protects against both UVA and UVB rays, is one of the most popular physical sunscreens - and it is an ingredient in most physical sunscreens. Because it leaves a white, flaky finish, it is best combined with zinc oxide, which is one of the most powerful UVA protectants around. Unlike the thick, white stuff that surfers and lifeguards once wore, today's zinc - which also goes by the names micronized zinc oxide and Z-Cote - is transparent.

How to use sunscreen

When it comes to sunscreen, how you use it is as important as what kind you use. Make sure you use enough sunscreen for the protection you need. Don't rely on moisturizers or makeup that contain sunscreen. These can be additions to your sun ­protection routine, but it is chemically difficult to blend a strong, broad-spectrum sunscreen into a moisturizer or foundation. You're safer using actual sunscreen as your primary defense against ultraviolet rays. Sunscreen needs a few minutes to meld with your skin before it can do its job. That's why many sunscreen labels suggest applying at least 20 minutes before sun exposure. Reapply even if a product says "waterproof," "rub-proof," or "all-day formula." Why? According to some dermatologists, most sun screening agents have a 2-hour span when they're most effective.

Many sunscreens are heavy and greasy, which makes the acne-prone among us tempted to forego sun protection altogether. Experiment with light, oil-free gel formulas instead.