I'm no expert, but I'll just give you my two cents.
Your shop is really cool actually :) It has a lot of interesting stuff. It's also good that you realized that your business slowed down once the new tagging system came to Etsy. I've looked at several of your items (you have a good number of items as well, so there shouldn't be a problem with that). Some of your item titles are a little too simplistic. Try to put in more keywords, the important keywords being in the front of the title and the less general, more detailed keywords in the back. Also, to help people find your shop on Google, you might want to change your "shop title" (jeeze, julia! this stuff's neat!) to words that describe your shop; leave the shop title to your banner :).
These are the things that I have researched, since I don't really have much experience (I only have 20 sales, haha). But best of luck to you and I hope your sales rise soon!
Regards,
Michelle