I love these earrings:
http://www.etsy.com/listing/61027216/bumblebee-fabric-stud-earrings... and i would use them in Treasury in a second IF the main photo zoomed in on the earring more so I could really see what they were in the first photo. The only reason I clicked on the item was because of the world Bumblebee (and I love bumblebees!). I think that you did choose the best photo in terms of light quality and crispness - but try taking more! When I first opened my shop I spent practically all of my time taking and re-taking photos. I would get so frustrated and overwhelmed sometimes but eventually my photos did improve. I am still learning. There are still items in my shop that are on the list of photo re-shoots,
Regarding the number of items in the shop - this has been so true for me. For my first six months I had about 25 items in my shop consistently. I was making a few sales a month. I set a goal to make and list a new item every single day. Within a month my sales had increased dramatically. When I finally reached 50 items in my shop, my monthly sales actually tripled (granted, the numbers are small potatoes, but they were huge baby steps for me!). I even sold more in January than in December. Of course, there were other factors: my work evolving and diversifying, the onset of Activity Feeds, my photos becoming more 'Treasury-friendly'... but the commitment to increase items in my shop inevitably increased my skills as well.
Other things that have worked for me: updating my tags regularly based on Merchandising Reports and Etsy Emails, then re-listing the item; making lots of Treasuries featuring other people's work; going above and beyond with customer service (i.e. treating my customers like the gems that they are). I hope this is helpful for you!