From my dermatologist:
(go get yourself checked out & let's have a safe Summer)
Sunlight contains two types of rays - UVA and UVB - both contribute to the development of skin cancer ... and wrinkles! Your sunscreen should be broad-spectrum, meaning that it blocks both UVA and UVB rays. Look for a sunscreen that contains at least one of the three following ingredients: Parsol 1789 (avobenzone), titanium dioxide or zinc oxide.
-For daily use SPF 15 is sufficient. If you will be involved in outdoor activities you should use a sunscreen with SPF 30 or higher.
-Apply the sunscreen 20 minutes before you go outside, and reapply every 2 hours.
-Sunscreen should be applied liberally. Don't forget to apply to your ears, neck and scalp (if your hair is thin).
-Use other methods of sun protection as well - cover up with clothing, wear a wide-brimmed hat, and find shade! Try to avoid sun exposure when the sun's rays are the strongest, from 10 AM to 4 PM.
-Sensitive skin - try Neutrogena Sensitive Skin SPF 30. This product contains titanium dioxide only, which is considered a physical blocker and is less irritating.
-Acne prone skin - gel sunscreens are less likely to clog pores. Shade, Coppertone, Presun and Bullfrog brands make gels.
-Thin hair - hats will afford the best protection but if that's not practical try a spray sunscreen. Examples are Neutrogena Sunblock Spray, Ombrelle Spray Mist and PreSun Mist Sunscreen.