While considering the obvious places to apply sunscreen (face, shoulders, back of neck), remember your not-so-obvious places as well. Like under your shirt, just above your waistline. Because when you are bending over pulling weeks for 3 hours on a windy day, your shirt will not stay over your pants and your back will be exposed to sunshine.
And sunshine is not kind on your lily-white behind.
(And yes, siblings, I know I do this every year. Because I seriously do forget. Do you think I enjoy being in pain??)