I haven't done any whole serious sprites in awhile, so I guess I'll just start off with some line-arts.
From Left to Right: From Memory>Looking at Reference>Cleaned Up
Anybody can color it if they want to.
I would say his body needs to be longer and his legs need to be shorter and smaller. his thumb is also on the wrong side of the hand near the bomb.
I don't like the knuckles on the right hand they look awkward. I like the idea seems nice. If it's possible you could try and move the right leg a bit to the right and make it touch the floor or make the feet be in a position that touches the floor. If you don't mind I would like to take at spin at coloring it, when you finish it of course. I want to see if I have improve in some way with my coloring/shading.
One hand is a lot smaller than the other.