Ok, so i finally read through all of this and i think I can help you out.
There are a few main things to take into consideration when you're choosing colors.
1, Are they warm, or cool colors?
This roughly means, do they have blue shades, or red shades in them? Violet, Blue, and Green are your main cool colors, whereas Orange, Red, and Yellow are your main warm colors. Interestingly though, you'll find that all colors have both warm and cool variations, and that's where the color selection comes from. (Well technically all primary colors have this. Secondary colors like Green and orange look awkward when they involve the wrong shade. For example, if you mix a red with a little blue in it, with yellow, the orange comes out being muddy and kind of gross) When choosing a color composition, you want to maintain a warm or cool color set unless you want something to really stand out. An easy way to get your colors looking the right way, is to lay down a base that you're going to use for the general tone of your image. What I'm trying to say is, instead of painting on a white background, paint on a muted burgundy or a vibrant blue, that way you'll know what kind of color set you need, as well as what your reflective colors should be. And this brings us to our next point.
2, Know what reflective colors are, and how they change your drawing.
http://www.anticz.com/drawing1.htm go to that link and scroll down a little until you see the random shapes. Note that on the rounded ones, the gradient shade goes from white, to black, to
gray This is because of reflective light, and you very well may have known this already. What you probably didn't know, is that the reflected light is the area where you take colors from different parts of your image and implement them into your drawing. For instance, if a woman is wearing a blue shirt, her face may have shadows on it outlining her chin. As the shadows bend around her jaw, they will turn a shade of blue to match the shirt she's wearing. It's bizarre that this happens in real life but is so seldom noticed.
And there are my two tips specifically for coloring. As for my opinion on the dude's loincloth? try using a gray-blue like his hair, and add some skin-tones in the reflective light. (and some blues in the skin) It should make your coloring job look more balanced. *nods*