Okay, I'm going to make you start over.
Follow these steps.
1) Make a new document & place render where you want it.
2) Copy the render 4 times and move to places you feel they should go.
3) Merge the 4 copies AFTER you move them (ctrl+e)
4) Move the render above the 4 you're about to smudge if you havn't already.
5) Smudge. Mess with the brush settings, [Window -> Brush(F5 for CS5)] Use a brush like "chalk" in the default brushes.
6) Add C4Ds under the Render, NEVER PLACE THEM ABOVE THE RENDER LAYER. Erase parts you don't like.
7) Add a few Gradient Maps, but make sure not to over brighten it. I like the Violet, Orange on soft life with a lower opacity.
8) See if you need to force lighting, this can be done with a white soft brush about 150-400px, if there is natural lighting in your signature, dont follow this step.
9) Is it to bright? To dark? There's a brightness/contrast adjustment layer for that! :)
10) Make a blank new layer, no color[no white/black either].
11) Go to Image > Apply Image and it should take what you have and put it on your blank layer.
12) Go to Filter > Sharpen > Smart Sharpen (I'm not sure if CS3 has it) my usually settings are 50% at 1px.
13) Name and a Boarder.
Now I know it seems like a lot, but it really isn't. Please post results of a new one :D