Color Matching in a Nutshell
Color matching is an interesting area, because people with refined taste can easily generate color combinations that are immediately beautiful even to the untrained eye. While the best examples of this skill can be found in art museums (look at the colors on some Vincent van Gogh paintings, for example), there are countless lesser but still impressive works done every day in the print advertising industry: Some magazine advertisements are very beautiful, and actually border on art, themselves.
Why should the average person care about color matching? Two reasons come to mind: Dressing and shopping. Given that adults and older kids are expected to be able to dress themselves, one might as well look as nice as possible. And one must not forget that many products do come in a wide choice of colors---not just shoes/clothes, but plants, cars, consumer electronics, etc.---so the typical person should have some degree of color-matching skill. Sadly, most people have no training in color matching, and this shame is visible to the whole world---but easily rectified!
If you look in your local bookstore, you will find numerous books that teach color matching. However, it is very simple to "mechanically" match colors to a surprising degree, and I explain how to "memorize" a color wheel so you can drop color matching knowledge anywhere that it's needed.
Be warned that color matching is a dangerous mental virus, because once you start to understand color combinations, you start to notice things, everywhere---for example, in many magazine advertisements, on well designed flower beds, and so forth---and this is because many kinds of designers spend lots of effort on color matching in a surprising number of contexts. (Color matching can also be fun, for what better foundation for a blistering fashion critique/tirade than ill-matching colors? Meow.)
The Color Wheel
Simple color matching is based on a "color wheel," and you can read about it in countless books on color matching (actually, contemplate doing a search on the term, as lots of information is available on the Internet [although a book is still better, because the examples can be printed with exact colors, a luxury probably beyond the scope of your computer's display]). But, for our purposes, we should think of a "color clock," where each number of the clock is painted in a different color. If I call noon "0" instead of the usual "12," the clock would be colored as follows:
- 0 = Red
- 2 = Orange
- 4 = Yellow
- 6 = Green
- 8 = Blue
- 10 = Purple
Ah, but what goes at one, for example? Well, one is half way between red and orange, so it is red-orange. Indeed, nine is blue-purple, and so forth.
You have to memorize the above order of colors, i.e., you must know that green is six, for example.
Attractive Color Combinations
Let n be any color that you want, represented by its number on the clock. Then attractive colors that go along with it are given as follows:
Colors n and n+6 always look good together. These colors are on opposite sides of each other on the color wheel.
For example, orange  and blue  go well together, as 2 + 6 = 8. Red  and green  go well together, as 0 + 6 = 6.
Colors n-1, n, n+1 always look good together. These are colors that are next to each other on the color wheel.
For example, red , red-orange , and orange  go well together (n=1, for this example).
Adjacent Complementary Colors
Colors n, n+5, n+7 always look good together. This is picking two colors that bracket the complementary (n+6) color. So, for example, green  goes well with purple-red  and red-orange .
Sometimes the colors n-4, n, n+4 look good. This is just picking three colors on the clock that are equal distances from each other. Orange , green  and purple  are one example (n=6), and red , yellow  and blue  is another (n=4). (There is only one more such example left; can you find it?)
Colors n, n+6, m, m+6 sometimes look good. This is like throwing in two arbitrary colors and their complementary colors. (Personally, I'm somewhat suspicious of the tetrad theory.)
A. You are at the mall with your cousin, and he wants black wool pants, a nice blue  shirt, and a tie... so, how can you help him? One choice is the complementary color, 8 + 6, or orange. If that's too wild, another choice is an adjacent color, and that would be blue-purple  or blue-green . You might also want to look at something that's a triad, so you'd look at 8-4 and 8+4, or yellow and red.
B. Let's say your friend's wife picks up a yellow blouse, but wants advice on accessories. You know that the color is 4 [yellow], but you might want 9 and 11 (adjacent complementary colors). So, you pick out some accessories in blue-purple  or purple-red  and see how they look. (Think of the "adjacent complementary colors as being the colors around purple , the actual complementary color... sadly, this sounds like expensive jewelry.)
C. You are at the mall trying to buy sneakers for your niece, who always wears blue jeans. What kind of sneakers should you consider? You could get the same color (8), black, white, a neighboring color (blue/purple or blue/green), or perhaps the complementary color, orange.
I hope that you enjoy your new color-matching skills, but then develop them well beyond the modest scope of this small article!
Kleanthes Koniaris, email.
A "mathematical" note: Some people might ask, "if I want the complementary color of purple , that's color 16, but what does that mean? 16 is an "alias" of 4, or yellow. But how did we know that 16 "equals" 4? We are free to add or remove 12 from any number to get it into the range from 0 to 11 (inclusive). If this concept doesn't make sense to you, it is also possible to rephrase the question, "what number plus six is equal to ten [purple]?" You'll get four, or yellow.