The summer means beach volleyball, backyard cookouts, and soaking up as much sun as possible after a long winter trapped indoors. For many sun lovers, all those sunny poolside afternoons come with the added bonus of a tan. Sure, we’ve all heard that burns are bad and that your SPF number should be somewhere in the neighborhood of Stephen Hawking’s IQ, but really, how bad could a little sun be?

Honestly? Pretty bad. In the U.S., five million people are treated for skin cancer each year, according to The Skin Cancer Foundation. The foundation also claims that 90 percent of non-melanoma skin cancer cases were caused by ultraviolet radiation from the sun.

So if you want a healthy glow, maybe you should consider a spray tan. If you want to protect your skin, you should really invest in a good sunscreen. But what SPF do you really need?

Related: Sunscreen and More Mud Run Gear That Plays as Tough as A Mud Runner

According to Dr. Lance Brown, a board certified dermatologist with offices in both New York City and the Hamptons, you need to be using sunscreen with a high SPF and reapplying frequently. “Typically SPF over 30 is sufficient, but the higher the better,” Brown says.

However, most people aren’t applying their sunscreen nearly enough for it to be effective. Generally, you should be reapplying your sunscreen entirely every 2-3 hours (or more, if you’re sweating or swimming). Dr. Brown says that if you’re going to be in the sun from morning until night, it’s smart to pack a bottle of sunscreen for each person in your party. “You should really be using a full 8 ounce bottle of sunscreen if you’re going to be at the beach all day.”

And if you’re planning on using other products, such as moisturizers, on your skin, Dr. Brown says it’s best to apply sunscreen first. “Applying the sunscreen first is thought to be the best as there is some concern that other products may dilute the sunscreen by inhibiting it from making direct contact with skin,” Brown says. “If you must apply other products in addition to sunscreen, it is best to use makeup and moisturizer that include sunscreen as well.”

And finally, don’t just lather up the parts that burn. It’s important to shield your entire body from the damaging effects of the sun. “Make sure you get your lips, ears, back of your neck, hand, and even the soles of your feet,” Brown says.

Learn more about prevention…

Go Ahead, Cop a Feel: Men’s Health Info You Should Know

Achieve Total Wellness Through Hormone Balance

Fighting the Fog: Surprising Strategies to Prevent Alzheimer’s