I've only been doing this since Aug, so take this with a grain of salt.
I think your banner is cluttered. The dog pic makes the lettering look dirty.
Click on the rearrange your shop button and don't have your featured items right on top of your latest items. Then it just looks like duplicates.
I think your gift certificates are cute, but maybe too wordy?
Your pencil sketches are really pretty, and overall, I think you are on the right track. My shop is cluttery, too! Argh! Constant maintenance. (Seriously, my 2 cents on this could be worth only 1 cent).
:) Staci