It needs a lot of work but at least you didn't add c4ds. c4ds = fail. You are better off using stocks then c4ds. The sig is too plain imo, you need to add more to it not just brushes. Try not to always center your render, movie it a bit to the left or right whatever suite you best. This sig lacks lightning, you can see the lightning from the render but you need to implement where it is coming from to give it a good lightning effect, a soft white brush will help with that. Work on your depth, you can add good depth by blurring the BG a bit and using the burn tool on the sides. I can't really tell you to work on your color choices since its in black and white, can I see the color version of the sig? Flow is good, you can tell where its coming from. Contrast is good. Blending could improve by adding more things to the sig. Nice job.