Nik, I didn't mean to leave you hanging, but life intervened . . . let's keep a couple things in mind here. First, I'm working from a couple of images, while you have the figure in front of you. Second, there's a difference between technique, and style.
From the images, I think the shading is a bit on the weak side. From a technique perspective, each of the quilted squares (diamonds?) should have both a shadow and a highlight. The fabric puffs up toward the light in the middle, and is drawn away from the light where the stitching is. Add to that the normal garment shadows, and there's plenty of opportunity to be a little bolder with the contrasts. (Still talking technique here...)
You ask about shading/highlight colors - you have a "tan" base color. I would mix a little warm brown into whatever color you used for the tan shade, and shade with that. I'd use a lighter tan or warm white with your base color for the highlights. I'd go a bit darker in the dividing lines with a brown wash, first, and then do my shades and highlights.
Another method is the so-called "dark-to-light" approach. When I first tried to paint with acrylics, it was a mess. I couldn't control the contrast - it was either tiger stripes, or too subtle. Then I stumbled on a article by a wargame figure painter, who talked about priming in black, and moving from dark to light only. I tried it, and suddenly it made sense. (Paint color "triads" was my other saving grace!) Now I think of where I want to end up, and move from the dark shades to the lighter shades, with much more control, and transitions that are much more pleasing to look at.
The same approach can work with artists oils, too. By lightening the initial color mix, a range of shadow-to-highlight tones can be developed.
Which brings us to . . . style. If you're a frequent visitor to this site, you know that there is a bit of a divergence these days regarding the amount of shading an artist might use on a figure. There are some painters who seem to be pushing the contrast limits with each new figure they do. Deep shadows, strong highlights, lots of difference in "value" (strength or tone of a color). Some of this is driven by what the fantasy painters are doing with color and contrast. On the other hand are painters who take a more traditional approach to contrast. My bias is probably with the "realistic" crowd, artistically, but I study the technique of the contrast painters.
What the heck am I babbling about? Look at the folds of the cloak behind the figure's right shoulder. Based on the image, I think you have your shadow and mid-tone colors in place, but are lacking the highlight color. Again, based on the image, I would hit the tops of the folds with a couple brighter shades of red, to emphasize the parts that are receiving the most light. Same for the green of the sleeve - it looks like the underside of the right arm, and the top side, have the same color value. The underside should be (slightly) darker than, and the top should be (slightly) lighter than, the "base" or middle green color.
Now, on the leather bag, I see some lighter tone around the edges, which looks good. It breaks up the brown color, and adds visual appeal. Maybe one more shade lighter on the edge of the flap would pop out that detail even more.
Of course, maybe all this is really there, on the figure, but the lighting washed out the contrasts, or the camera just couldn't provide an image that really shows your work to the best advantage.
Nik, I hope some of this will be helpful. Bottom line - be a little bolder - push for one more highlight when you think you've done enough, and see if that doesn't produce a pleasing result. Best of luck, and KEEP PAINTING!!! All the best, Don