Most of us know we’re supposed to wear sunscreen and some of us even know how to pick out the right kind. Hint: Choose one that’s broad spectrum with an SPF of 15 to 50. But once you’re armed with the right sunscreen, do you know how to use it? If not, read on: The New York Times interviewed several dermatologists for their pro tips to help you apply and reapply correctly:

• How much to use? Use an ounce of sunscreen (enough to fill a shot glass) each time you apply. You may need to adjust that amount depending on your size.
• What kind to use? Use creams and lotions over spray-on sunscreens, as there is little research on their effectiveness and on the health implications of inhaling the spray. That said, some experts still maintain that spray-on sunscreen is better than nothing, while stressing that it’s important to spray with caution, avoid your face, and spray in a well-ventilated indoor area.
• When to apply? Apply sunscreen 15 minutes before exposure and reapply every two hours and after swimming, even if the sunscreen is waterproof.
• Where to apply? Apply to all the usual suspects (legs, arms, back, shoulders, etc.), but also remember the extremities you usually forget, like the tops of your ears, the tops and bottoms of your feet, and your scalp and neck.

Source: New York Times