I have a handful of Artizan Designs Wild West minis, and each one has plenty of character. This one reminded me so much of Colonel Sanders, I could not resist this particular color scheme.
As with all limited palette exercises, maximizing mid tones is very important. This is where you can tint colors the most, such as a grey that is more tan, or more greenish, etc. Mixing a light flesh tone with a dark grey or even a black will get you a far different tone than mixing black with a sky blue, for instance.
I attempted to get some yellows into the mix as well, especially on the hat. You can see even more of the blueish grey on the pants, although there is also some greenish grey. A similar set of light and dark shades were done on the base.
One of the five "color theory" videos I did as part of the kickstarter focused on grey, showing how 'grey' can be more purple, blueish, yellowish, and so on. And yes, it was called Shades of Grey. I will have that at Reapercon along with the rest of the video collection.
He's also here: