Dr. Marie Jhin, a dermatologist in the SF Bay Area, answers your questions about sunscreen.

We are so excited for long beach days and afternoon picnics in the sun. But as we all know, a great way to ruin a sun filled weekend is a sunburn. In order to keep you happy and safe all summer long, we have put together a few sunscreen tips to help you before and during your time in the sun!

At the store:

Look for Broad spectrum (UVA/UVB) coverage and an SPF of at least 15.

Get to know your sunscreen: read labels and find the best sunscreen for your activity and skin type. Do you tend to have sensitive skin? Opt for oil-free. Are you going to be swimming or playing sports? Get a waterproof or sweat proof sunscreen.

Experiment with different formulas to find what works best for you. If one brand makes you break out, try another.

Before you go outside:

Shake your sunscreen bottle well, then slather on a full shot glass worth of sunscreen on your entire body 30-45 minutes before you get in the sun. Apply a quarter’s worth of sunscreen on your face.

Remember those easy to forget places like your ears, feet and the parts of your scalp that are exposed to the sun.

When you are in the sun:

Applying sunscreen in advance of going outside is a great idea to make sure your skin has soaked it in before sun exposure, but remember to reapply sunscreen to any sweat-prone places before you get outside. The backs of the knees are an important place to reapply, because sunscreen commonly rubs off while driving or sitting.

Reapply after excessive sweating, swimming, or every two hours.