Damn, too bad FloaterTWO didn't use hi-res tex I made. Low-res throws itself into eyes. Nice composition, tho if I were you I would not overdo contrast so much and use more lamps instead for a more dramatic darker look.
Don't have it saved sry, but I can write some tips. For lighting use a lamp with a regular round sprite selected, outside of frame. Point it at your scene and move it around (use camera tool to preserve the shot and move around). Lamps create more solid shadows and also add more ambient and dynamic lighting to the shot. In my "Come back" shot I have two lamps. One over top (dark-cyan) and one behind the guy (purple). The closer you bring a lamp to your object the brighter light becomes. Also the higher your cross at the colour pad to the top, the brighter your lamp will be.
I know about basic lamp tips, but I always mess up on the colors and FX, as I'm never sure what color filter to use (I have a pack from a video tutorial on Facepawnch and a few of my own) in my screenshots, or what color lamps to specifically use for specific shots/moods.
Choose colours according to environment. Night has lots of cold colours, so warm ones will make bright contrast. Day has more warm colours, therefore use colder ones and so on. It has a lot to do with intuition, there are no "proper" or "wrong" colours.
It's the M4 of the Mass Effect series. But technically, it shouldn't be the M8 Avenger. Alliance soldiers are all issued Aldrin Labs or Hahne-Kedar equipment, as stated in one of the books. The rifle should really be one of the many M8 lookalikes known as the M7 Lancer,(even akin to how many god damn lookalikes there are of M4s/M16s) because they are all, like I said, given Hahne-Kedar stuff. Kahlee Sanders once noted a fake Alliance soldier simply because he wasn't using Hahne Kedar stuff...
Yeah, they're really good at that. Like kinetic barriers stopping biotic attacks, for example. It's kind of sad when the fans know the lore better than the actual creators. Or care about it more, rather.