If it's any consolation, I am taking a makeup artistry program, and my instructor has not given us any specific rules about eyeshadow colour. You have to play around and pick stuff that looks good on the person that you are working on. With creativity, you can make any colour work. There are so many different variations of specific colours, you are bound to find something that suits someone.
We had an older lady come into our classroom for a demonstration. My instructor did her makeup infront of the class. She told him that she loved blue eyeshadow. He hates blue shadow, but he made it work for her. He combined some great shades, and put it on very subtly. She looked amazing when he was done.
I believe that there are no rules. If you look great....go for it!