Gday Jack, welcome to the forum
. Well, where to begin with advice... it's a big piece so there's a lot to scour...
I'd say there's three main things you should address first:
- anatomy and poses of the soldiers
- colours of the piece
- shading
Since you say you mainly just draw for fun, I'll assume you don't know too much about various techniques, so I'll try to link to articles about them where I can. You might want to acquaint (or reacquaint) yourself with some
colour theory, first off. The colours in this piece for the most part are all very saturated (especially the trees). You can vastly improve the look and feel of this setting by toning down alot of the saturation. I think your picture could especially benefit from some
aerial perspective, also. Following that vein, the sky is too saturated and too dark, I reckon. Also, there's too much contrast between the clouds and the sky.
As for anatomy, the right-most soldier's arms are too short, and I think his legs might need to be a teensy bit longer (same with the other guys). Apart from that they seem to be pretty good.
And last but certainly not least, shading! Your piece lacks pretty much any shading at all. You should determine a lightsource (perhaps a midday sun overhead) and shade accordingly. This will be alot of work, but it will bring some much needed depth to the piece, not to mention beautify immensely.
That's all I've got for now, good luck with it.
