I know I haven't been the biggest jimmy up fan from the start, but considering I do this for a living it's hard to look at some of these designs. You guys really need to practice your illustrator skills. This isn't being a dick, this is a fact. The curves look awful and the perspective is way skewed. Get on some online tutorials and read, read, read, practice, practice, practice.
Compare this to what you have:
http://img85.imageshack.us/img85/394...0sx02zomh8.jpg
**link posted not as an advertisement nor to insight competition between zilvians, I have no affiliation with said designer.
I suppose it doesn't matter, it seems people like your designs and buy them. But from a design standpoint, you guys just need more practice and design sensibilities.