This is not a bad first go Im at work so cant make a full coment on this But some quick advices 1. Lightning check your lightsourceses, the light on the soldier and the chopper does not look like it comes from quite the same places. also the shadows are way to hard, soften them out making them more realistic. Another example look at the soldier walking towards you light comes from top or slightly above from the left, but shadow falls in front of him? see the mountain above him, light clearly comes from the left side on that so the light on the solider would be from something similar to that.