1. People are getting rid of bookshelves. Treat the money you budgeted for shelving as found money. Go to garage sales and cruise the curbs.
2. While you're drafting that business plan, cut your projected profits in half. People are getting rid of bookshelves.
3. If someone comes in and asks where to find the historical fiction, they're not looking for classics, they want the romance section.
4. If someone comes in and says they read a little of everything, they also want the romance section.
5. If someone comes in and asks for a recommendation and you ask for the name of a book that they liked and they can't think of one, the person is not really a reader. Recommend Nicholas Sparks.
A delightful list and the rest are here.