Protect your skin! Always wear sunscreen on exposed skin; read the bottle and follow the directions. As a general rule of thumb, try to put sunscreen on 15 mins before going in the sun and then reapply every 2 hours. This will help prevent sunburn! Wear a hat (or a helmet if biking!) on the trail to protect your face and scalp from getting sunburn. The sun is also harmful to your eyes. It is good to invest in a decent pair of sunglasses that provide UV protection.
Source: https://cerinic.com/journal/2020/06/28/summer-hiking-tips/