Here's some constructive criticism, I guess...
In my opinion, and that's all it is...
If you slap a render onto a background and play with filters and lighting, it usually won't turn out to be something that is particularly unique, catchy, or even quality.
When you said, "I could do better", well...that could mean a multitude of things.
If you're talking about just filters, then I guess, yeah, you could scroll through some values to your liking. "Better" is subjective. To our liking? That's not inherently "better". If you're trying to achieve a more "objective" definition of better, I would consider looking at some tutorials and mastering some techniques. Then you can incorporate it to your work. At the very least, your understanding of how images fit together will improve and your overall approach towards graphics will result in a better understanding.
Here are some tutorials that will make the piece more "personalized" instead of just finding wallpapers you like. You might be able to create something you like and you'll get more out of it.
http://www.hongkiat.com/blog/40-cool-abs...tutorials/
http://www.vandelaydesign.com/photoshop-...-textures/