Come summer, mosquitoes happily feast on our exposed skin as we swat them away in hopes of avoiding itchy bites. But before you break out the bug spray, follow a few smart rules to make sure you’re using it safely.

Most insect repellents use one of three active ingredients: DEET, picaridin or oil of lemon eucalyptus. All three are generally considered safe if you follow the directions, according to the Mayo Clinic.

Here, a few smart do’s and don’ts.

Related: What Bit Me? Mystery Bug Bites Solved

Do: Cover up with clothing, such as long sleeves, to reduce the amount of exposed skin. Then apply repellent only on bare skin.

Don't: Spray it directly onto your face (instead, spray it on your hands and then pat your face) or near food (DEET is toxic if swallowed, according to the Centers for Disease Control and Prevention, and can cause stomach upset, vomiting and nausea according to the National Pesticide Information Center). Use it sparingly around your ears, and don’t spray on cuts or irritated skin.

Do: Use only a small amount. You’re applying insect repellent, not spray-painting a car.

Don’t: Use a product that contains both an insect repellent and sunscreen. Why? Sunscreen needs to be reapplied more often than bug spray should be used. Also, according to the National Pesticide Information Center, sunscreens that contain DEET may cause more DEET to get into the body through the skin.

Do: Match the concentration of DEET with how long you need protection for. Most people think higher concentrations work better, but in fact, they just last longer. Products with less DEET (concentrations range from 4 percent to 100 percent) may be appropriate if you're going outdoors only briefly. Don’t bother with products that have more than 50 percent DEET; studies indicate DEET concentrations over 50 percent don't last longer than lower concentrations.

Related: How to Treat Bug Bites

Don’t: Let young kids handle repellent. Apply it to them yourself. Don’t spray their hands because they might put their hands in their mouths and eyes.

Do: Wash or bathe after using repellent, especially if you have been using it repeatedly, advises the CDC. If a rash develops, wash the repellent off with soap and water. Call a poison control center for further guidance and keep the bottle handy in case a doctor needs to examine it, the CDC advises.

Don’t: Use DEET on children under 2 months, according to the American Acadamy of Pediatrics. And never use a DEET concentration of more than 30 percent on children. Also, the CDC recommends against applying oil of lemon eucalyptus to children under three.

Do: Use an insecticide called permethrin on your clothing for extra protection when you need it; just don't apply it directly to your skin. The CDC says to treat your clothes 24 to 48 hours before wearing them to allow the permethrin to dry. It stays active on treated surfaces through multiple washes, according to the CDC.

Do: Check the label for a registration number from the Environmental Protection Agency (EPA), which will read something like “EPA Reg. No.” followed by a series of numbers. Registration means the EPA doesn’t expect the product to cause adverse effects to human health if used according to directions.

Check out the EPA’s online search tool for help finding the right type and brand of repellent for your needs.

Related: Natural Mosquito Repellents: Which Ones Work?

David Arv Bragi is a freelance journalist and marketing consultant. He has been writing about health and safety issues since the 1990s and currently lives in Portland, Oregon.