What color should I dye my hair?

With your fair skin and bright green eyes I think a brown would be best on you. A light or a dark would work, but don't dye your hair black. It won't look good, and there are other reasons why you should just stay away from that color. Look at Miley Cyrus for example, she has light-ish skin, and green eyes. Her brown hair, (both light and dark) in my opinion look good on her. Totally up to you though!