thats sum good advice from dinero i'd take that on board... u need to somehow learn to make the background seem further back, it looks like the dudes got a wicked hair style spannin the whole sig lol, try tone it down a bit or make the edges darker or something.
your light source in v1 is great but as u can see on v2, it floods with white and looks bad, turn down the opac of it on that one
great improvements i'm seeing from you, keep it up...
scout the net for sum free brushes u can boost into ur sigs, it helps with blending renders into the background to take out that sharp edge
or sumtimes i select the outline of the render, go down a layer and contract by 10 pixels feather to about 10-50 pixels, then fill with black so theres a black/white fade around the render, adjust opac/fill to suit or change layer properties, then brush some bits to make it flawless under on ontop of render...
mid way amateur 3