Color choice is the first artistic decision we make when painting a miniature. It can be an arduous and harrowing decision (especially if we spent hours upon hours converting a miniature.) 

                                       "Goblin Shaman" by Jaroslaw Camelson Drabek
                                              http://www.puttyandpaint.com/projects/498
           Jaroslaw has taken a bit of a bold move here by combining green skin tone with some blue body paint (on the chest.)  Color theory tells us that green (blue combined with yellow) has an opposite of red.  The mushrooms and the ponytail contrast very nicely with the green and provide a harmonious balance.  Blue however, doesn't belong in any color scheme based on the color wheel.  It's just too close in color to the green to be complimentary, so it has to be used in contrast.  The shaman has this contrast used to great effect by making the face in green pop out from the chest in blue to truly bring your focus to the center of the figure. Nicely done.

http://www.puttyandpaint.com/projects/617

               Florian has used the same formula here, but switched the blue to the primary color, with green as a solitary spot color for his hero.  A rusty orange provides the contrast in this unit, present on the hellsmith as well as the flame.  The blue armour provides a fantastic contrast to the dark look of the unit itself, elevating the figures beyond the background and into the viewer's focus.  The bright green goblin shrunken heads provide a fantastic spot color to allow the viewer to pick out the hero even while on the edge of the unit composition, in contrast to the freehand loincloth of the hellsmith.  The difference highlights the magical nature of the caster, and provides a great narrative without words.
                                              "Trolls Fight" by Jaroslaw Camelson Drabek
                                                http://www.puttyandpaint.com/projects/493
           And now, we're back to Jaroslaw ;) Scroll back up and take a careful look at the Goblin Shaman once more.  If I'm not mistaken, you'll see almost every color in this diorama is present on that little shaman as well.  The solitary missing tone is the red contrasting tone from the mushrooms and ponytail. By eliminating the red, Jaroslaw has formed a very cohesive tone pallette, with muted colors providing a contrast that is not present in more traditional color theory.  The blue and green providing a striking contrast to focus the viewer on the defender suggesting as well the eventual winner, making the right troll appear more virile and stronger.             Choosing a non-traditional color scheme can really make a piece stand out from the competition, but it truly requires an exceptional skill level to "sell" the complete composition.  Also, try a test model first (such as a clampack mini ;) ) to make sure you can put the vision in your mind onto the sculpted surface.  This juxtaposition of traditional color theory and color tones most likely contributed to the golden demon this diorama won.