Okay, i see what you want.. you want some strait critisism ?
I will state my oppinion and give you some tips .. and if you will still make crap, im sorry i cant help you .. i think the sigs suck .. they dont have proper blending on the render .. you have no vocal point on the sig .. the txt sucks .. no blending .. all you do is .. slap in a BG .. slap in a PIC .. and slap in TXT .. that's not art anymore .. that's called wasting your time on crap .. so if you don't want people to think that your sigs suck i suggest you to read some tutorials (
GameRenders - Your Source For Free Gaming Renders / try googling " Photoshop Tutorials " /
deviantART: where ART meets application! ).. i all quote this as IMO which means IN MY OPPINION .. I wish you good luck on your further learnings ..