1. I read the "bad" review. To me, this is just bad customer service. You should always be aware of your stock. If your items are made to order then declare so, by putting down 11 in stock you claimed you have 11 ready to ship items. If you ran out of stock by any reason, apologize, refund. Do not send another item! Also, protect your work with things like bubble mailers.
2. Photo Photo definitely look unprofessional. You don't need an expensive camera to take good stock photo.
https://www.etsy.com/listing/252453250/zombie-brain-cupcake-phone-charm?ref=shop_home_active_2This one is partially corped when you view it on an Etsy page.
https://www.etsy.com/listing/254029843/league-of-legends-inspired-poro-earrings?ref=shop_home_active...Keep the object the center of the photo.
3. Variety
The small amount of item make your shop look amateur-which may not be too bad but I personally prefer larger store with more items. People may be attracted by one item and come in to see more!