in stage work, i learned a couple neato tricks with colors. put yellow and green together and it makes people have to pee. think back to any sample in the jar and, if you remember, those were the colors used! you can make people feel cool or hot with various colors (tweezer always had black spaces and bright whites with blues and greens and yellow to make you feel freezer-ish). red and blue together will strain the eyes if used too long (think 3D glasses). and you always have to double check the costumes under the lights to make sure that your lights don\'t change the color of their costumes.
as for \'rules\', not really, but lots of handed down knowledge mostly gained from finding out the hard way.