In the Summer you need higher than spf 15. Spf 30 is a good bet, in the winter though spf 15 should be okay. I use Priori sunscreen thats spf 30 and i use that all through the year. I'm terrified of getting wrinkles you see :[ I wear it with moisturiser though and its fine. Although its pretty pricey just for a bit of sunscreen I think i pay Â£16 and its only a small bottle but if you use just a tiny bit on your face and then use something different on the rest of your skin its okay because it lasts nearly a year anyway.