This is just my personal opinion, but I think I would start by cropping in your thumbnail so that the prints are easier to read. By thumbnail I mean the photo that is seen when your shop is open to the first page and you can see a few of your listings. I like the way they are displayed in the same frame and look very uniform. I think they would be better for the thumbnail view at least if all you saw was the outside edge of the black frame. Another suggestion would be to have a nice banner made on fiver. They are only about $15 U.S. and really add a professional look to your shop.