I'm cautious because I don't react too well to sun exposure. I try to avoid the sun between 11 and 3 o'clock.
But I have two friends who are more sensible, they've freckled skin and red hair. One had to wear a hat and repeatedly use high factor sun cream when we went wandering, or his skin would start to peel.
K-Tipp/saldo tested the six most popular sun sprays and creams, and an alternative that contains only mineralic filters, in 2006. The PDF (available
here) is worth a download. For those who don't know German, the important rows in the table are "Abweichung zur Deklaration" (deviation from the declared protection factor in percent), and "Wasserfestigkeit" (water resistance retention). Not factored in, but mentioned nonetheless, is that Weleda, Garnier and L'Oréal don't contain a substance that is suspected of being hormonally active (OMC Ethylhexyl Methoxycinnamate for the boffins

).