Corey,
sorry for the confusion.
How I do it is to get a base colour I am happy with - either straight out of the bottle (rare) or one main colour, adapted to suit needs.
For example, the red on my centurion figure.
Base was Red, with some burnt umber to reduce the intensity.
Then I shifted the base coat toward orange for the highlights by reducing (or eliminating) the burnt umber, and adding orange/ yellow
For the shadows, increased the ratio of burnt umber to base, then for deepest shadows, added a hint of black.
Its about ratios of colours to each other. 7 parts this to 1 part that, 0r 2 parts x colour to 3 parts y colour
click the link, entry 12 will illustrate how I work out base, shades and highlights
http://www.planetfigure.com/forums/showthread.php?t=28570&page=2
With a bit of experience, experimentation, and the occasional 'well, that
didn't work" you will rapidly get the hang of shading your own colours.
often, you can get colour mixes from basic colours, rather then lashing out and getting elf snot yellow, orc booger green and space marine ear wax tan, for example.
hope this clarifies.
cheers