When creating templates for the presentations, colorful headers for the documents, layouts for the brochures, quite a few people rely on the feeling of the color scheme which is basically trial and error and you know it feels right when the colors match. Obviously there is a pattern/rule/law for the matching colors. Colors can we warm or cold, bright or dark, with high or low contrast. There is an online tool that might help in picking up the matching colors for you. I think it is a pretty nice tool for the mentioned purposes. Take a look.