Hmm.The quality of render is really low.The rest staff is good.
About suggestions.
I have to say that you have to change the main render.Brush on it and make a clipping mask,give it some depth by blurring it and use some C4D's on lighten/color dodge/overlay with lowered opacity.You can also add a b&w gradient on normal,30-50% opacity.
Regards,MD