things you need to work on

blending:it looks like the renders on a layer of its own just on the top of everything its very slap and stick , try using c4ds and effects to melt the background and the forground together so they look like there meant to be together
background:while i guess it has minimal depth it could use allot of work , you have tried to mix the 2d elements of what i asume are brushes on softlight with verious ammounts of c4d renders that also just seem placed , just finding ways to blend the renders together using smudging or displacment maps , adjustment layers such as colour ballence and curves layers could help you achieve this. also i personaly would never repeat my render in the background so visibly you should use your render for colouring maybe to give you an idea of how to blend it into the background but i can see a faded face its not a good look bro.
type(ography) : again it looks just slaped on in there work on making the text fuse with the image to compliment , make it obvious without making it distracting
size:try working on a smaller canvas i found when i was starting out that the smaller the canvas was the less space i had to worry about filling try some thinner sigs maybe on a 400pxls wide by 110pxls tall , see if you find that easyer.
and last but by no means least read as many tutorials as your eyes can handle

keep at it and dont forget to have fun