couple of remarks
the signature would come out better if you minimized the canvas a little bit. It would give better dynamic to the signature. Also try using some shading/lighting. You can easily do this with a black/white/other colour soft brush and then changing the layer settings to (vivid light, soft light, hard light) or changing the opacity to 20-60 percent.
Even though you could have done more with it, but how did you do to the background? You got like a spilled liquid on the back.
Anyway keep up the designing!
I'd give it a 4/10, still some work to do, but it has potential!