Make sure to use your sunscreen!
For babies under 6 months of age:
The two main recommendations from the AAP to prevent sunburn are to avoid sun exposure, and to dress infants in lightweight long pants, long-sleeved shirts, and brimmed hats that shade the neck to prevent sunburn.
However, when adequate clothing and shade are not available, parents can apply a minimal amount of suncreen with an SPF (sun protection factor) of at least 15 to small areas, such as the infant's face and the back of the hands.
For everyone else:
Avoiding sun exposure is still advised.
Use a sunscreen with an SPF of 15 or greater that protects against UVA and UVB rays.
Follow the directions regarding re-applying, especially after swimming or sweating.
Sunscreen least likely to cause allergic reactions have Zinc Oxide or Titanium Dioxide as their active ingredients.