Theyre nice but it would help if you posted the original stock url so we could see what exactly you did to them.
As far as the sig goes...
1) Work on your render cutting skills. From what it looks like, you used the magic wand, but there are still some white spots surrounding the render
2) Work on matching the render with the background, and trying different ways to blend, rather that just blurring and all the old boring stuff.
3)Try making a background rather than just using a single fractal.
4)Its a bit too big to be called a sig.
5)That is all...Good work
