We’ve established that color communicates mood, emotion and space. It has a push/pull effect that can make a colored surface pull forward or push back. It mixes in the eye to make new colors. A colored ground or a thin glaze on the top of a painting often serves to unify the whole and adds depth to the work. Repeated color helps create surface harmony and lead the eye. Color that “clashes” creates tension and color interacts with color to some surprising effect. Using the color wheel can act as a guide but experimenting is probably the best way to get a command.
Paint is pigment mixed with a binder. Historically pigments were made from ground minerals, oxides, carbon and lead. Mixing these elements involved great skill because their production and interaction left the end result unpredictable and unstable. (Simple history primer of pigment from Winsor Newton- http://www.winsornewton.com/about-us/our-history/history-of-pigments/ )
Now much of the muddle of paint-mixing is taken care of with the modern manufacture of paint. There are some principles that are handy to know, but most useful knowledge of paint-mixing, in my opinion, comes from trial and error with attention paid to the results.
Here is a link to an “About” post by Marion Boddy-Evans that is a good sum-up of color-mixing. http://painting.about.com/od/colourtheory/ss/color_theory.htm It’s nine pages long and has a lot useful info. But I find it hard to get through because I am impatient and all I want to do is start squeezing the tubes and watch the colors dance. If you’ve seen my collection of tubes you know I don’t spend a lot of time mixing. But because I’ve done it enough, I usually know what I need to combine with what in order to get the desired result. And if it doesn’t work, sometimes I just change directions and that’s ok too. For me, it is the discovery in painting that I find alluring, so I’m not necessarily tied to the results. But if you feel more comfortable with knowing, read the two links (and then share what you think is most enlightening.)