There is a product (sorry I forgot the name) that you can wash your clothes with that makes then protect you from damaging sun rays.It lasts through several washings. It can be found at Walmart next to the Rit Clothing Dye.
You can also purchase clothing with built in sunblock at Sporting Good stores. I highly reccomend this for warm climates! Kept me burn free in Costa Rica, Belize and Panama! 8)