If you really want to run a good card shop you have to do it the Japanese way. One shop here (Mint, in Shibuya Tokyo) has an actual bar in the store, so you can have a beer at the counter while flipping through cards. I haven't been to it yet, but THAT is a killer idea.
This is their website (its in Japanese but you can see some pictures of the shop and its bar)
http://mint-web.jp/?pid=39086084