How can I fade my tan?

I'm quite pale which I don't mind, but I have a tan line on my arms from wearing a school shirt to school during the week. Same thing with my skirt. How can I even out my tan or fade it? Even though I'm pale, I tan quite easily, which is not good when my tan lines become more defined and look odd. Also, I'm going to wear a bikini in the summer for the first time and I'm wondering how I prepare the skin that hasn't been exposed to the sun much at all? I don't want to get burnt! I'd hate to have to deal with all those crazy melanomas and such. Help asap!