I read an article recently by a dermatologist. She said the higher the SPF the better and to apply VERY liberally. One product that she recommended is Coppertone Spectra with an SPF of 50. I used it recently prior to a round of golf. Afterwards I had NO tan line so obviously it worked. I don't know if your goal is to not burn or to protect your skin. If the latter, then I would recommend maximum sunscreen and no tanning bed.