The Top 10 color tips on this HGTV website include the 60-30-10 rule, which means 60% for the main color, 30% for a second color, and 10% for the accent color. In a room, this usually means 60% on the walls, 30% on the upholstery, and 10% with an accent piece. This obviously is a guideline, not a rule. One accent piece?! What about patterned upholstery? And draperies? Get out of this box now!
Link: Top 10 Tips for Adding Color to Your Space : Decorating : Home & Garden Television