its not bad. the 3 tips i have are:

1. Work on making a focal, at the moment the sig is a bit over everywhere, and while this is fine in its own way it makes it harder for the eye to focus.

2. Colouring, this is very monotone. In future pieces try to work in more colours, but dont go over the top and work in colours which dont fit with each other.

3. Text, text can be hard to get right, i've got a tut on it in the tut section if you want, and often if can be better just to leave it out.

Hope those pointers helped