OK, I know I am a broken record, but, seriously, SPF every day. Do it. And if you need help finding a good sunblock, here you go. In college, I spent Summers working at a surf shop, and the one sunblock we recommended every time was BullFrog ($8.45). It doesn't rub off, it goes on well, and it keeps the sun's rays at bay. Or check out Aveeno's Active Naturals line (about $10 and under); it blocks UVA and UVB rays while staying light enough to wear under makeup.