I'm pretty much a novice really in terms of what I know, so take the following with a pinch of salt:
It's pretty good dimensions wise, only two things I would pick up on are:
1. Your purple and brown colouring on the jacket and trousers may be clashing a little. If you blend a little of a common colour into both, you'll get a more complimenting palette.
2. I've been pulled up in the past with using shades that aren't very visible so this may help you too. I think you could use a little more contrast on the jacket and trousers and boots just to get those highlights popping a bit more. Mostly on the boots though, the shading's difficult to see on them as it is.
Looks good otherwise, so just a couple quick tweaks there I reckon.