http://i54.tinypic.com/254ygzo.jpg
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Seems a bit flat and plain, bruh.
The C4D placement is good, but your blending with it is off.
You need some stronger colors to bring out your depth.
Some popping effects would also help and work with your lighting some more.
I'm guessing it's coming from in front of him, but that's a bit weird.
Kiu!
seems very simple and basic.
KIU
The major problems here are the lightning and bleniding.
I don't see any lightning at all but if add it your sig will look 10 times better then it looks now. Just take a 100-200 pixels soft brush. Look at the render and decide where the lightning is comming from. In this sig I guess that would be from right above him. Use your burn and dodge tool to optimize the lightning. :)
Also the render needs to be blended in more. I see you placed some c4d's behind your render. I would take the same sort of c4d and place it also in front of the render. So you create blending and at the same time better depht. Maybe you could also smude some parts of the render ;)
I like the colors you used tho I would change the brown BG color into something more blue And I see you worked on the depht. It just needs a bit more work.
Keep it up mate :D