Good for being a beginner!

But as you can't improve without knowing your mistakes:
First signature:
The render of Zed has a bad looking white border
(Can be solved easily by selecting layer's alpha,reducing selection by 1 pixel,inverting selection and deleting the parts if you're using Gimp)
Adding a bunch of shadows would fit well the light between Zed
Second signature:
TOO much red,moving lee a little to the right would improve the signature's first look. (when you see it the first time,your eyes will be directed to the fist mainly)
Also those two black lines aren't awesome IMO
Last thing: try to make the images a bit bigger
