My Maybelline foundation is too dark?!?

Recently I bought the Maybelline Dream Matte Mousse foundation for the first time. I really couldn't decide on the colour in the shop since there were no adequate mirrors around (!), and I ended up buying 'Fawn, 040'. Unfortunately it is too dark - and too pinky I think. Since I spent 7 odd pounds on it I still have to use it, is there any way I can make the shade better? And in the future, what shade should I buy?