The Color Coach says: "Think of color as a language. It helps you convey a message by setting a mood for your project. Just as you make a statement with words or images, you make a statement with color. If words are what you say, then color is part of how you say it." The combination in which you use color will have a great effect on how your project turns out because colors influence each other in how they are used together.. In many cases, you can substitute colors of a similar hue and change the look of your projects.
Until you become comfortable creating color combinations, you may want to just stay with TWO colors --- your main color and one accent color. If you want to use 3 colors, think of a paint swatch. Use the most of one color, half as much of the second color, and half as much of the third color as the second color --- walls, trim, and accent colors.
Also mentioned in the Color Coach: "The most powerful color tool is your sight. The human eye can distinguish over 10 million colors." No wonder I love to play with color.