Tolkien built one of the deepest fictional worlds ever imagined, and readers who love the films or the two famous novels often do not know how to go further without getting lost. Plunge into the posthumous legendarium too early and the density of names and ages can defeat you. The way in is an order that moves from the accessible classics to the mythic core to the tools that illuminate it all.
This path treats Middle-earth as concentric circles. Read the stories Tolkien polished for readers first, then the deep mythology behind them, then the reference works and criticism that reward a return trip.
Start with the classics
Begin, as generations have, with The Hobbit, Tolkien's warm, brisk adventure that introduces the world without demanding much of you. Then The Lord of the Rings, the epic that made Middle-earth a cultural landmark, deepens every element the earlier book touched. These two are the front door; read them before anything else.
Descend into the deep mythology
Now go inward. The Silmarillion is the Bible of Middle-earth — the creation, the elder days, and the tragedies the later books only allude to. It is harder going, which is why it comes here rather than first. Unfinished Tales of Númenor and Middle-earth then fills gaps with material Tolkien left incomplete, and Tree and Leaf collects his essay "On Fairy-Stories" plus the story "Leaf by Niggle," revealing the philosophy of sub-creation behind the whole enterprise.
Use the maps, guides, and scholarship
With the stories in your head, reference works come alive. The Atlas of Middle-earth by Karen Wynn Fonstad charts the geography and journeys so the sweep of the tales becomes concrete, and The Complete Guide to Middle-Earth by Robert Foster is the indispensable encyclopedia for tracking its thousands of names. Finally, for interpretation, The Road to Middle-Earth by Tom Shippey — himself a philologist like Tolkien — explains how language and myth generated the world, the single best guide to why it all coheres.
Read in this order and Middle-earth opens by degrees rather than overwhelming you at once. Follow the full path to travel from the front door to the deepest halls.