Pretty good for a beginner. Still, the renders are kind of bad (choppy). You need to blend them more. Maybe blend the text a bit too. Also, the yellow sparkly stuff... doesn't really go with it. I think. The Darth Vader one's background doesn't really seem to suit either.
Just my two cents/pounds/euros/yen/whatever. I'm not very good at critiquing. Also, I know what I said is mostly negative, ignore that. You're just starting out, my first signature /sucked/. You can see all mine at
http://www.darknet-f...signatures.html.