Atomic speaks the truth.
btw, about tuts, i personally dont use them so that's fine if you dont want to, but I think if i had to go back and relearn sig making i would use tuts, because it really accelerates the learning process. learning from someone else is also helpful, but it takes longer, this usually means you get a slightly more in-depth appreciation for the skillz but w/e either way is good.
if you go to
http://nationalsigleague.com, they have a lot of EXCELLENT sig makers(not artists, sig makers) and people who know of great tutorials. also, the battles are a fun and helpful way to test your abilities against someone else.
btwx2, that new sig is much better, it has a nice focal point and ok depth. the background is kind of uninteresting though, and the contrast is too high.
a good way to make you render look better is to duplicate it, then put a gausian blur on the duplicate(around 2.0), set the blending option to multiply on the blurred one, then set fill opacity to 80%, then go to the original render layer and put the filter sharpen on it, for most renders this will make it look much better quality wise.
also experiment with using c4d renders, find some on deviant art, select areas that will flow with your render(or just look good with the style of render because you can always use free transform to rotate it) with the lasso tool, give it a feather of either 8, 10, or 15 depending on where you're putting it in correlation to the render, duplicate the layer and put a gaussian blur on it(2.0 again), set blending options to lighten, then go to the bottom layer and put it on sharpen. makes renders look a lot better and more interesting--try not to do ONLY that though otherwise it's kind of lame, mix and match different parts of a render or different part of different renders. be creative, experiment.
that's my advice.