I really wish I could actually do GREAT signatures. Seems I am just stuck doing only mediocre work forever. That or I am just tired. I am tired, I know that much. I may or may not pass out soon. Until then, Kyoshi madness.
Your signatures aren't bad at all, they just all have a very similar feel to them. Maybe try deviating from your style a bit more or try a different medium (wallpapers, etc.)