Here is the first signature with GIMP...the other one well...it's not to be mentioned so here it is!
First Sig - nice, but the render is a bit on the blurry side.. Have you learned how to render yet? If not, then sharpen the render up a bit. The background is nice, but you should really concentrate on adding some smudges and filters (whatever you like the most, I'd duplicate the background, then grussain blur it by about 4. After that, make a transparency layer, and filter it with some Clouds or Plasmas. Overlay both, with the original background as the base. And for your render, don't ever merge the render til you're done with it, like sharpening, etc. Also remember to play around with the layer settings like opacity, and such.) If you're going to smudge, then use the brush name "Vine", and with around 20% or 40% opacity. However, duplicate the layer first before messing with the smudges. Possible, you should dodge the Riku render a bit so it can stand out a bit. All in all, pretty nice. Second Sig - I see you learned how to make a pop-out now... but your attempt lacks depth. The thing is, when people make pop-outs they just let the render be the center of attention. People ALSO pay attention to the background! So make sure the background is as good, and have the background to have similar colors to the render. As I said for the first sig criticism, needs more works. It seems to me like you're using abstract brushes. Try to broaden the brushes you use in any artwork (but if you want it to specifically just be abstract, fractuals, etc. theme artwork then just use brushes classified as that), and mess around with the brushes to yield better results like disortions.
