I know it's terrible, I'm a horrible beginner. I'm posting this more of a, "later I can look back and see how bad I was at the beginning. Don't bash it too hard, just tell me what else to do. I'm terrible with brushes.
I would work on the bg more than anything in the wallpaper. It is a bit plain and it is also hard to tell what the bg exactly is. You want to add something in the bg whether it is stock photos or brushes. It would be too hard to tell you what specific brush to use since its more of a feeling but thats what you should work on first. Then, I would add some render effects which you can find in our tut section. I believe Pinoy posted it. Also try to make your wallpaper fit the whole desktop whether it is 800x600 or 1024x800, etc.
Do some tutorials or something. It helps you know all the tools on photoshop, and how to make everything fit together.It's just the beginner stuff. But you'll learn to make motion blurs look really good in a sig and stuff like that.Also make sure your text fit the main colors, or black/white.Hope that helps.
Thanks, if I ever get something else somewhat decent, I'll post, I just wanted to at least post my very first.
Background needs work thats your main problem add soem pics of a city or him doing a play then use stocks photos to add texture and learn some lighting effects , just keep practicing and you should come along soon.