I think you should stop going gung ho into photoshop and actually get down and dirty with some tuts from www.dutchdesignz.com
That sig really is like a 4/10, it looks like you just grabbed some grunge brushes, made a quick background, placed a choppy render in there and slapped some text on.
But thats just my opinion.
To me a grunge sig should be more like this
But after all, I made that
PS: You beat me to making a crank dat sig >.> bastard






