Actually, what's your purpose as a Catholic bookstore? Do you really have a reason for being in business? Apart from selling Catholic stuff, why do you do what you do?
If you don't have an answer, I strongly suggest finding a purpose. Once you do, you will find that you start coming up with a lot more ideas on how to improve and promote your store.
First, I would propose that anyone who opens a Catholic store needs to decide that they are really opening a Catholic store. The first, and only reason that I can think of to justify opening a Catholic store is that you want to strengthen the Faith. This sounds like it should be obvious but it really isn't. Take a look around your store or think about other stores you have visited. Do all of the products in the store help to strengthen the Faith? Are there products in the store that contradict the Faith or muddy what the Faith is? If so, the store is contributing to its own and the Church's downfall.
This may sound harsh but it is true. If you truly want to run a Catholic store it has to be Catholic. Otherwise you are helping to sow seeds of confusion and dissention. Selling books by authors such as Fr. McBrien, Fr. Greeley, Sr. Chittister, Anthony deMelo, etc. may bring you a certain type of customer for a while but you will find that eventually this audience will shrink and vanish because these authors present views antithetical to the Faith and people that buy in to these authors' views will eventually leave the Church or stay on as aging dissidents who don't have much use for Catholic stuff and certainly won't be passing the Faith on to their children. If you don't believe me, just look at the destruction of the religious orders that adopted dissenting views after Vatican II. Most are either gone or have so few young vocations that they won't be around 50 years from now. If you don't hold to the Faith, there is no reason to stay in business or recruit for vocations or be evangelistic.
So, what do I do once I decide that I want my store to build up the Faith? (Part II)