One of the primary focuses of my series of sequential painting workshops is color theory, most importantly the values of colors. Without a full range of values, a painting can look flat and uninteresting. Here's another section of my Eden painting, shown in color and grayscale. When you compare the two, you note that the colors I chose, contrast nicely in both color and grayscale.
I only have the first two workshops completed and on the website, but eight more are in the works: http://www.drawspace.com/classrooms