Yeah search for some tuts if you arent using any, and go to DeviantART and search Vypas, and download his brush packs. They're great, expecially for starters.
As for the sig, it needs some work. I'm only being honest, 2/10.
-Black Outlined render
-Text blends TOO much
-The background seems pre-made. Go to PlanetRenders and get some C4Ds and stuff, and have fun with it.