I'm no pro, still struggling myself but I would say your on to a great start and it does take time. The biggest thing is getting found so work on tags. I notice lots of jewelry sellers have neutral backgrounds to allow the items to be displayed some of your backgrounds are a little distracting and the items are so cool you wanna enhance them (I'll be back for those arrow earrings). As far as the number of items someone told me once that you should aim for at least 50. I'm still working on that. Facebook is grea,t stay active and discuss things not just related to business, I get a much better response that way.
As for target audience I struggle with this as well since my shop carries anything from shabby chic to modern decor ect. But it is also a good thing because the different tags will bring a variety of people to your shop. The earrings I faved are right up my alley and I usually search: unique earring, eclectic, even bohemian or kitsch some terms that might bring the audience your looking for. Hope this helps.
Best of luck!
- Jackie