The color transitions are rather violent, and there's a lot of negative space. If you're going to make the tag larger, you have to fill it more, else wise it'd look better if you just crop it.

Take a look at this color wheel:

http://www.sanford-artedventures.com/study...iange_wheel.gif

That's a good place to start when thinking about color. Pick colors that are next to each other (like violet and red) on the color wheel, or colors opposite each other (like blue and orange). Clearly you can't just pick any blue and any orange, then put them together. Hue does matter.[/b]