Maybe stick with large art.
I've been making tags for the last year and I'm starting to move into LP's.
I also recommend practicing some basics...composition, execution, atmosphere, lighting, effects, depth, blending, flow, and others.
At this point, I can't really tell you to add or remove things until your work is less one smash-up of stuff, and more of one organization of elements with the basics down pat.
If you haven't already checked out Deviantart, I would do so and look at tutorials.
You should just be able to search them.
If you have any trouble, let me know, and I'll grab some from the Fringe academy that have helped me.