Well, the first thing I noticed is that you have some awesome artwork!! ^-^ That beside, I love the fact that your artwork is in the background of your banner, and the the words that you use get right to the point. The color scheme is very in touch with the theme of your shop, and that is a great selling point also.
Now, all I can really say to improve your shop banner, and make it even more aesthetically pleasing, is to examine how your fonts are set. I love that your 'earth love' is in a font that looks actually handwritten, which goes with the handmade quality of your shop; however, when I look at your second line, 'really cool upcycled stuff... and awesome art too,' I see a problem. In order to blend it more with the color scheme of the art that is behind it, I would recommend a similar shade of blue as to the streak of light blue that is to the left of your phrase. I also notice that you're using a pseudo-serif type of font.
Quick lesson: a serif font is the kind that has little 'wings' like in Times New Roman and Georgia. Although this type of font is very common in printed materials, like newspapers, it is more difficult to read on a computer screen due to a computer screen being a lower resolution. If you take a quick look around your screen here you'll no serif fonts. They're harder to read on the web, so are rarely used. That second line in your banner, as a result, is hard on the eyes.
This brings me back to my point: your second line may be a little difficult to read, but character spacing may also be at fault. Character spacing is the blank space between each letter in a word. Most modern word processors are designed to avoid inconsistent spacing, which looks odd and unprofessional, but some design programs, like Photoshop, don't do this automatically.
Take a look at the word 'awesome' in your second line, and then compare it to the 'awesome' typed on this page. Specifically, look between your a and w. That's a large space there... and it's a bit disconcerting.
The only other problem I have with that line is that it's also too small. No particular reason, but the easier I can read it the more likely I am to read more.
These should be easy fixes for your tech guy!
Reference:
http://dev.opera.com/articles/view/fonts-for-web-design-a-primer/
