Summer is here. It’s time to have fun. But, before you dare go outside, you will want to protect your skin from the hot sun. If you’re like me, your head will spin just by looking at all the different sunscreens on the market. So, how do you know which one to buy?

First, it’s important to understand that there are two types of sun rays to be concerned with: UV-A rays which causes damage that leads to wrinkles and brown spots, and UV-B rays which cause the actual sunburn.

Now that the science lesson is over, it’s time to pick an SPF (Sun Protection Factor) that’s right for you. Don’t worry, all those SPF numbers may seem confusing, but I will decode them for you. Normally, your skin will burn in as little as 10 minutes of sun exposure. An SPF 15 screens out 93% of UV-B rays. So where does the number 15 come from? Well, simply put, it means that you can stay out in the sun 15 times longer than if no product were used for 150 minutes.

Does that mean an SPF-30 has double the protection? No! Actually, any sunscreen with an SPF 30 or higher will provide only 97-98% protection from the suns UV-B rays.

So, what number is right for you? Obviously, the more protection you have the better, but don’t waste your money on products rated above SPF-50 because there is no effective way to test them.

Did you notice that while I was decoding the SPF rating system, we were only discussing UV-B rays or the cause of sunburns? That’s because the SPF system does not rate UV-A protection. So, be sure to look for products labeled Broad Spectrum Protection, as well as water-proof sunscreen. They will last longer because they don’t wash off the minute you jump in the water or have a little fun playing ball.

Once you have found the sunscreen that’s right for you, remember that no sunscreen will provide you any benefit—if left in the bottle. Many people quickly smear a little sunscreen over the body and assume they are protected for the day. Here are a few tricks to help get the most out of your sunscreen.

Double check the expiration date on the sunscreen—to make sure the actives are still good—as well, shake the bottle before using to help make sure its mixed and not separating.

Next, apply sunscreen on you and the family 30 minutes before going out in the sun. The active ingredients need time to be absorbed in order to be effective. I suggest that you apply sunscreen before you leave the house and even before you put on your bathing suit.

The key is to make sure all areas are covered with sunscreen—not just the areas you think will be exposed. Cover feet, legs, torso, arms, hands, back, shoulders, neck, and face. Pay special attention to the ears, lips, eyes, and scalp (especially for guys with thinning to no hair). And since most sunscreen lotions can drip and irritate the eyes, consider a stick sunscreen for the face and around the eyes. Try it! Your kids will thank you for it!

How much sunscreen should you use? Sunscreens are formulated so the average person uses about one ounce. That’s a lot more than you may have thought, but skimping on the amount you use only defeats the purpose and minimizes the benefits.

Another secret is to reapply, reapply, reapply! That’s right— reapply every two hours you are in the sun, or even more frequent if you have been swimming or sweating.

With melanoma cases on the rise, it’s critical that you properly apply your sunscreen and continue to reapply it, especially if you are going to be in the sun for an extended period of time.

David Pollock is a global beauty expert who has formulated products for some of the most recognized names in the business. He is a published author, radio personality and was recently named one of the "20 to Know" by Global Cosmetics Industry. Today, David is empowering women to take control of their health and beauty. Subscribe to his free newsletter at www.JustAskDavid.com.