Not being mean, but yes there is a lot you can improve on.
First of all, you put all over your effects all over the mustang which is your focal.
You should try putting your effects more around your renders (the mustang) and a few on the edges of it to help blend into your background.
Also you should have had someone render that out for you in render requests and create a background your self.
And you seem to have a pretty basic idea for Photoshop now so you should just open up a blank file put a colored background in with a render.
and just goof around with every tool and filter you can tinker with, don't worry about how it looks just get some ideas on how to make effects
To use in your art work. So with that said, for the mustang signature I'd say take the effects off the mustang and try adding some effects around the side.
If you got any questions about anything or some effects you want ideas for or something PM me and I'll help you out if you want.