See u r pretty good, this just needs some refinement
To start its a little blurry so play around with the shapening tool+options a bit see what you can get.
The colours fine, it looks good to me
Something which would make this sig so much better would be some smudging on the render, especially his web i mean wtf it just stops flat :p
Play around with the smudge tool on the render.
Your text isnt awful but id apply a clipping mask to it, itll blend a lot better.
You got a pretty good light source so ill leave that out
Its a little simple, try adding a few more C4D's and maybe some brushes or pen tooling. Also id add a border, 1px black, it'll ramp it up a bit too.
Its a great start just needs a little bit of work.
Gl, hope i helped.