Ahh, you're off to a good start. I assume you have some experience in other forms of art
?
The main problem I see with it is that the upper body, including the arms and weapon, lacks a true sense of depth. The legs do really well there though, but you could stand to get rid of that light band around the back leg's knee.
Also, the only color range with good contrast is the legs, most else is either dark or light, which doesn't really work here.
Lastly, if you're using a reference it's privvy to post it
.