Ok, let's start with this.
Nice choice of render. The render itself has depth and that can help with the rest of the job. Placing is also good.
Not so good stuff: BG is too dark, render is too bright. If u can find similar BG with daylight just replace your BG with it you will see that it will look much better. So, you have problem with working on light. To solve this problem u will have to have main lightsource in your tag for a start which will always guide you in chosing the right option for the lights in your tag. Now, having said this lights are also part of blending in the tag and u have to work more on blending here. Not just when it comes to lights but also dont be afraid to use different elements to help render look like its part of your BG. BG choice would be good if you darkened the render, put differend C4Ds or some other elements (I prefer different pngs) and work on lighting there but you cant just put a render on the BG and expect it to look good.Text is meh, probably the nightmare for most GFX-ers except Horus, hehe, but hust practice with it and you'll be good.
Anyway, thanks for posting a tag in this sea of avatars and hope I see more of your work soon. Good job and KIU!
_@:Yeah.
I can agree with everything there. XD Would it be too much to ask if you could point me in the direction of a/some good tutorial(s)? 
I'll keep at it. *_*Yeah, I'm gonna try and post one with every avatar thread I make. :erm:
Cool.
Glad you like them.
Thanks.
