nice ava's of hussey, i like the 4th one.
hazard siggy is also good.. definitely one of your best but still hav a long way to go. follow some simple and basic steps for signature or ava.
1) take the render/ stock, provide it a suiting bg
2) add some render effects, use brushes or textures but to a limited amount. don't over do! (i personally dont use them much mainly because m not good at using them)
3) give a proper color tone to your work
4) at last add text using suitable font with suitable color, judging by the emotion the gfx is conveying or u want it to convey!