The following are the sun protection recommendations given by FDA:

Reduce the time of exposure to the sun, especially during the period when the sun is strongest: 10:00 am – 2:00 pm.

Multiple sunscreen: in addition to sunscreen, you can wear long sleeved clothes, hats and sunglasses.

Use SPF15 and above sunscreen products. If skin color is white, it is best to use spf30-50 sunscreen.
Apply sunscreen 15 minutes before going out, and reapply at least every 2 hours. If you swim or sweat a lot, apply it more frequently.

Apply enough sunscreen. Adults or children of normal size should use about 30ml sunscreen on their face and whole body each time (shocked? In fact, I am too).

Don't forget these easily overlooked parts: ears, nose, lips, back neck, hands, insteps, around hairline, and the part with sparse hair on the top of the head.

Sun protection throughout the year: as long as there is sun, even if the weather is cold, it is still necessary to protect against ultraviolet rays. Snow can reflect sunlight, and sunscreen products should also be used in winter.
It is not recommended to use sunscreen for infants under 6 months of age. Infants can wear long sleeved clothes or stay in the shade for sunscreen; Children older than 6 months should follow the instructions. The American Academy of Dermatology recommends sunscreen containing titanium dioxide or zinc oxide for infants and young children over six months of age.