I know that some quilts just seem to flow when I look at them and everything seems 'right' about that quilt. Most of that has to do with color selections.
Sara over at the blog Becoming Martha has some great tips on colors and an awesome color wheel that could be adapted to choosing colors for your quilt.
Once you decided the purpose and person for your quilt, then you could choose your colors based on what you want your quilt to say.
Check out her blog entry here...it's about choosing colors for your front door.