I pretty much have this all the time. ALL. THE. TIME.
* As said, browse the internet for color schemes.
* Use a color wheel and color theory to narrow down your palette. Try Adobe's Kuler.com and
http://colorschemedesigner.com/
* Might as well avoid colors that are difficult to paint. NO YELLOW.
* Likewise, if you're using black primer, narrow down to colors which work best with black primer. Same with white primer. NO YELLOW!
* When I was a wee lad, Chaos Armies *were* individualized. In this thread, notice that, while different colors are used, each *individual* unit has essentially only one color, with some contrasting (?) color.
http://warhammer.org.uk/phpBB/viewtopic.php?f=4&t=79381&view=next