Des, I think the figure looks great as is. Since the face and eyes have already been touched on, as well as blending of shadow and highlights, might I suggest dirtying him up a bit? What colors you choose will depend on what type of terrain and conditions he will be in, but a general rule of thumb I follow is to carry whatever he'll be standing in, onto his boots especially. I personally find pigments to be best for this.
I coat the sides, heel and toe fairly heavy, thinning the amount of coverage as I go across the the metatarsal area and up the boot. Also, depending on exactly what type of material he's wearing and whether he will be pre, or post, flight, maybe a few small oil or grease stains on his coat front. Maybe even a little thin black wash on his face, leaving it clean only where his goggles and/or scarf would cover.
Once I find out where I hid my workbench and finally get a chance to sit down and do something, I'll attempt to make two build logs to post. One on scratchbuilding, detailing and weathering a trench wall, and the other on detailing and weathering a figure, (yes figures do get weathered).