I like it. You've got a very nicely made signature their. The stock placement is ideal for the stock you use. I'm not really a fan of placing your stock in the middle but it looks like you've pushed it a bit to the right. I see that you've used a clipping mask (i think) which works well as it helps blend the stock into the sig. I do think however that it's a bit 'simple'. You could spice it up by maybe sharpening the main stock image. You could also try and smudge the edges of the girl or add a fractal. It's also a good idea to give your signature some sort of 'flow' or direction. At the moment you have them yellow rectangles exploding in different directions around her. Instead you could try and move them around the girl so that they are all facing the same direction and are perpendicular to each other. Keep trying! :)
It isn't bad, especially if you are new at this. Nice choice of render. A pointer I have to to add some darker colors so that the background has more depth and contrast to it. Taking colors from the render using the color picking tool is a great place to start. The edges look pretty empty because they are juse a solid light color. Overall, try to have more color variance and add more to the tag.
