As the days get longer, the outdoors beckon. But longer days also mean stronger rays.

Today marks the unofficial start of summer, and getting outside doesn’t mean you have to get a sunburn.

Avoiding the sun’s damage can prevent skin cancer — the nation’s most common type of cancer, affecting one in five Americans, according to the Skin Cancer Foundation.

Protecting your skin can also prevent aging, says Dr. Diane Rose, a Metairie dermatologist. Any tan is evidence of skin damage, she says.

“You’re more likely to get wrinkles and discolored skin and your skin is not going to age as gracefully as it will when you protect it,” she says.

Rose provides these rules to ensure your skin is safe this summer:

Cover up

The best way to avoid sun damage? Avoid the sun, Rose says.

Seek shade when the sun beats down the hardest, from 10 a.m. to 4 p.m. If you stay outside during those hours, cover up. Wear a hat with a 3- to 4-inch brim to cover your ears and neck, cover your eyes with sunglasses and wear clothing that blocks the sun.

Ultraviolet rays from the sun can penetrate clothing. A white T-shirt typically has a ultraviolet protection factor of 8 — an SPF rating similar to the weakest sunscreen. Darker colors and thicker fabrics work better, but may be hot.

Clothing specially made to protect your skin comes with an ultraviolet protection factor (UPF) with a rating system like sunscreen. Clothing labeled as “sun protective” must have a UPF of 15 to 50.

Love your sunscreen

If you must stay in the sun, wear a sunscreen with an SPF rating of at least 30, Rose says.

Which kind of sunscreen is the best? The one you like to wear.

“I really think the most important thing about sunscreen is that you like the way it feels, the way it smells and the way it rubs on,” Rose says, “because you are more likely to wear it.”

The most popular sunscreens are chemical varieties available in a lotion or spray form. These generally take 30 minutes to work, leave a colorless film on the skin and absorb the sun’s rays. Physical sunscreens — zinc oxide or titanium dioxide — reflect sunlight. Older versions of these were known for the chalky residue they left behind. Some new products do a better job of blending into the skin.

Whichever sunscreen you buy, make sure it carries a broad spectrum label. Broad spectrum sunscreens protect against two types of ultraviolet rays — A and B.

Apply and reapply

Apply sunscreen liberally.

Rose says you should apply at least 2 tablespoons of chemical sunscreen on your body, rubbing it in.

That’s the size of a shot glass or a golf ball. If you’re spraying it on, feel everywhere to ensure you didn’t miss any spots, then let it dry.

Before going swimming, apply sunscreen before you put on your bathing suit.

“If you move and your bathing suit moves with you, you might have things exposed that you aren’t expecting to have exposed,” Rose says.

When working or exercising outside, apply sunscreen under your shirt. Make sure not to miss the tops of your ears and back of your neck — two spots susceptible to sun damage.

Reapply sunscreen every two hours. Do it sooner if you are sweating excessively.

Be prepared

Rose tells her patients to apply a sunscreen with an SPF of 15 every morning, whether they plan to be in the sun or not. Some skin moisturizers and make-ups contain sunscreen.

“It’s a good habit to get in, and then if you find yourself in the sun unexpectedly, then you are protected,” Rose says.

Buy several tubes or cans of sunscreen and stash them everywhere so you are never without it. Put them in your bathroom, car, purse, workout shoes or in your golf bag.

“Planning for the day is probably the most important thing,” Rose says. “Know the potential exposure you might have.”