I had a load of fun with these characters. I love getting into their detail, their armor, and their weapons. For me characters are also a good way to try out new techniques and skills without getting bogged down with the complexities of a full illustration (although even in illustrations I am constantly trying to learn something new).
In this case, I wanted to try out using more opaque brushes in my work as well as really focus on a unifying color scheme. In fact, I think you can even see that transition in brush use from the green samurai to the other characters. The green samurai was done completely with a round brush with the opacity and flow set to pressure. In the other characters, I started using a harder edged opaque brush in areas as well (these are not the only brushes I ever use however, there are others). This not only drops in some really vibrant color that gets lost when using lower opacity, but hardens up some edges, and in general makes you think more about how you are painting. Actually, I should say that thinking about painting is not so much a consequence of brush choice, but rather trying new things helps you think about what you are painting in a more conscious manner.
Here are the characters that I did. The character from the full illustration and the geisha in orange were not my own designs but based on those of an image provided to me by Paizo, but the other characters' costumes were developed by me.
progress and detail:
I usually start with line art and then paint an opaque layer under (or over it on a multiply layer) to rough in colors. This speeds up the process quite a bit, as it gets the major color decisions out of the way.