Rule #4 - Pick colors on purpose

"Don’t just grab some colors out of the air. Know what the colors will do when you combine them and, more important, what they might mean to the audience. Color carries an abundance of psychological and emotional meaning, and this meaning can vary tremendously between cultural groups and even individuals. Color affects visual hierarchy, the legibility of type, and how people make connections between disparate items-sometimes called color coding-so choose wisely. Never assume that a certain color, or a combination of colors, is right for a particular job because of convention either. Blue for financial services, for example, is the standout color cliché of the past fifty years. Choose colors that are right, not those that are expected." Design Elements: A Graphic Style Manual, Stratham