Ever wonder why your skin feels sensitive after you’ve been in the sun all day? Maybe you forgot to reapply your sunscreen, didn’t realize it was expired, or forgot to apply it altogether. Don’t let this summer be all about aloe — avoid these common sunscreen mistakes.

1. You don’t know what SPF really means. The sun protection factor (SPF) indicates how much ultraviolet B (UVB) light the product will filter out. As a general rule of thumb, always choose an SPF of 30 or higher. According to the American Cancer Society, SPF 30 filters 97 percent of the sun’s UVB rays, SPF 50 filters 98 percent, and SPF 100 filters 99 percent. No sunscreen offers 100 percent protection.

2. You don’t know what type of sunscreen is better. Even if you use sunscreen correctly, some sunscreens don’t protect your skin against the sun’s other rays – ultraviolet A (UVA) rays – which can damage the layer beneath your skin and cause premature aging. Choose a broad spectrum sunscreen that protects against both UVA and UVB rays.

3. You think a high SPF means you can spend more time in the sun. Wrong. SPF is a measure of the time it will theoretically take you to get sunburn, but there’s more to it. Here's how it really works.

4. You apply sunscreen when you are outside. You should apply sunscreen 30 minutes before you go outside since it takes approximately 15 minutes for your skin to absorb the lotion. If you wait until you are in the sun to apply sunscreen, your skin is unprotected and can burn.

5. You don’t reapply sunscreen. You need to reapply your sunscreen every two hours for it to be effective and reapply immediately after swimming, drying off or sweating.

6. You don’t apply enough sunscreen. Dermatologist recommend applying one ounce of sunscreen, enough to fill a shot glass. Don’t forget to apply sunscreen to your ankles, feet and ears, and protect your scalp by wearing a hat.

7. You forget to protect your pout. Skin cancer can also form on your lips. Protect your pout by applying a lip balm or lipstick that contains sunscreen of SPF 30 or higher.

8. You skip sunscreen if you are going to be in the shade. Even if you are in shade and even if it is cloudy, you should still apply sunscreen. This is because UVB rays can reach your skin indirectly through scattered clouds, dry sand or concrete.

9. You ignore the expiration date. After sunscreen has expired, chemicals in the lotion can degrade or break down, especially if it has been kept in a warm place. If the texture or smell has also changed, toss it.

10. You only apply spray sunscreen. Spray sunscreen can lead to easily missed spots. Also, the Federal Drug Administration is currently investigating whether spray sunscreens are safe to use due to accidental inhalation. If you use a spray sunscreen, rub the sunscreen in once you apply it so your skin absorbs the lotion, and spray it into your hands first before applying it to your face.

Don’t fry this summer. Lower your risk of skin cancer with these 5 tips.