This is a timely comment for me. I have been doing research on opening a small indie (new/used) bookstore in a small old downtown I walk through almost every day. It has restaurants, specialty shops, coffee shops and a small local grocery store. I've always thought it was missing a bookstore.
Any tips/warnings that might not be immediately obvious to a hopeful bookstore owner? Do you think there is a sweet spot in terms of square footage of retail space? Margins are low so do you supplement with sidelines/events/memberships?
One of my next steps is to join the ABA as a provisional member to get access to their new bookseller guides.
I'm just an internet commenter who knows nothing about running a retail store and has thought about a bookstore as well. With that out of the way, finding high margin items to sell to offset low margin items would make sense. I think this is why you see coffee paired with bookstores, coffee should be high margin but might also require food licensing/inspections.
Ideas for a local bookstore: seasonal and local items for sale, think gift giving timeframes - mothers day, fathers day, end of year holidays. Items like unique greeting cards, calendars, custom gift wrapping, having a kids section with higher margin items kids like - toys, trading cards, etc. Also you could throw some checkout friendly things like book lights, book marks, candies, etc.
If you find local craftspeople, offer some shelf/floor space for free if you can agree on a split of the margin. Hand-crafted things would pair well during holiday seasons and advertised properly might get repeat visits and word of mouth spreading.