Once you understand the basics of color theory, you can start learning how to combine those colors into a harmonious whole. There are certain colors that look good together, while other colors look so painful you have to click away before they burn your eyes. And while you might recognize these combinations when you see them, there is a theory based on the color wheel as to which colors will look nicest together.
Analogous Colors
These are the colors that sit next to each other on the color wheel. For example: green, yellow-green, and yellow; or red, red-orange, and orange. Play with the hues and saturation of analogous colors to create a harmonious color scheme.
Complementary Colors
Complementary colors are those colors that are opposite one another on the color wheel. By using colors that are opposite one another, you create color schemes that have high contrast and so are brighter and more vivid. Some contrasting colors are: red and green or blue and orange.
Color Triads
By placing an equilateral triangle on the color wheel, you can create color schemes that have a lot of life to them. The most basic color triad is the three primary colors: red, yellow, and blue. But others are: green, purple and orange, or yellow-orange, blue-green, and red-purple.
Still Having Trouble?
When looking for color schemes the first place I start is nature. The color schemes found in nature are typically harmonious to our eyes. This can be the case even if the colors don't "go together" according to color theory.
Judy Litt, the About Graphic Design Guide, has put together a great library of color combinations for the Web. Web Color Gallery
