Begin with what you love about the book: its setting, atmosphere, themes, author, or a character's way of seeing the world. Those details are better planning prompts than trying to reproduce every scene.
Separate fictional places from real ones. Research author homes, libraries, bookstores, landscapes, neighborhoods, and museums independently, then verify current access, opening information, transport, and local conditions.
Build a normal, workable itinerary first and add a few literary anchors. Leave time to read, write, or talk about the book so the trip carries its mood without becoming a rushed list of references.