For the Basics: ColorColor is a well known factor in many outfits, not just on gaia. The color coordination method is used just about everywhere.
Color is easy to figure out.

First, you have your primary colors:
Red,
Blue, and
Yellow. These colors are the basics for any other color in the spectrum.
Next, the secondary colors:
Green,
Orange, and
Violet.
Finally, there are the more complicated colors- The tertiary colors:
red-orange,
red-violet,
yellow-green,
yellow-orange,
blue-green and
blue-violet. (yes I know these colors don't quite match up, but it's the best I could do for now. This will be revised when I have more time.)
There are many ways that a color scheme can be done:
A
monochromatic scheme is one that is done completely with one color and one color alone. You can use various tints and shades to do this kind of color scheme.
Example:

An
analogous scheme is one that involves the colors adjacent to the color you choose. Say you pick a red color. You can then choose to use red-orange and red-violet. They go with the color red.
Example:

Notice how the colors gradually get darker towards his feet.Next up is the
complementary scheme. This is a scheme that involves using the color that is the exact opposite of the one you choose. For example:
Blue-
Yellow. Blue and yellow are complete opposites. If you use these colors together, the blue and yellow will bring the other color out, thus enhancing the original scheme.
Example:

Notice how the blue objects bring out the yellow.
This is the
blending scheme part. Here we have the cool colors and warm colors. Colors are divided into the two categories.
Red,
Orange, and
Yellow are all warm colors, like fire.
Blue,
Green, and
Violet are all cool colors, like water. You can use the colors together to make uplift the other colors that you use. For example, if you used blue, you could use green and violet to bring those colors out more.
Examples:


You can see the colors blending together.
(more later...)