I've been watching this one for a bit. I was sorry to see you change it from the original concept, which in my opinion was better than this one for conveying emotion into the picture. (the one with the silhouette of the soldier) I thought it was quite good. (And before you put that flag in).
Other than the anatomy problems you have now, everyone else has commented on that: I would, try to get rid of that haze. (is that the scanner or something you purposefully did? Put the flag on a flagpole stuck in the sand or if you must have it on the person, drap it over his forearm. A soldier is not going to have a flag stuck to him like that, ( and as a matter of fact you might be insulting some Americans just by using the flag in that manner.)
I'd add some ripples in the sand, and shadows. Sand in the desert has a lot of ripples from the wind blowing over it. Also humps and hollows. Seperate your mountains and hills somewhat by adding some darker shadows in between them. Really dark at the bottoms of each hill/mountain.
You have a good concept here. Something that might help is to become the soldier, be that person when you're doing it, feel the sand in your clothes, on your skin, feel the emotion he's feeling. Feel the cold air coming off the mountain, the grit in your mouth, the gun in your hand. Put yourself there, you will be amazed at what will happen. Good luck with it, you've done a nice job on the color of the sand and the soldier, you just have to push it more.
Art gives me a life of extreme challenge, frustration, accomplishment and contentment. Nothing less will do!