That’s the fundamental question of the web, according to this terrific essay by Paul Ford. His advice for publishers?
Create a service experience around what you publish and sell. Whatever “customer service” means when it comes to books and authors, figure it out and do it. Do it in partnership with your readers. Turn your readers into members. Not visitors, not subscribers; you want members. And then don’t just consult them, but give them tools to consult amongst themselves. These things are cheap and easy now if you hire one or two smart people instead of a large consultancy. Define what the boundaries are in your community and punish transgressors without fear of losing a sale. Then, if your product is good, you’ll sell things.