i'm a gfx nub

Their not good. you really need some work.
I hate when people say thats really good for your level. You dont get much better from that do you.
and noobs commenting noobs cant be good so im just gonna add my fev lines.
yellow one
the texts is ugly, dont use so much layer styles and everything, keep it simple when adding text. And it contrasts way too much from the rest of the sig.
the sig is too plain. And try to make the background more eyecathing, making it somehow more fierce, and more contrast. Dont make it too contrasting so that you can tell every pixel.
Its unoriginal, try adding something of your own to it. When you improve a little try something else than that.
The only depth the sig has comes from the text and the text is ugly.
Dont use ctrl+u to color your sigs, use color balance layers.(layer>new adjustment layer>color balance...)

:mellow: i am not trying to bash/flame/diss your work.

Your current (reddish) sig is way too empty at the left, a good render, and goodish blending, then totally raped due to simply white text, kills it. The yellow- read the above post o.O

hmm to make that text look better, i'd use a better font, set the blending mode to soft light and give it a normal (not screened) black outer glow....

i would also more the render a little more to the right...

and im not really any good with depth (understatement) but it definately needs something because it looks a little flat...

I guess that dragoneye pretty much sums this one up. I know you can improve! Keep workin at it.