Start with The Crying of Lot 49. It is Pynchon at a hundred and fifty pages rather than seven hundred, it runs the same machinery — a search through a postal conspiracy that may or may not exist — and finishing it tells you honestly whether you can stand the mode. If it bores or irritates you, Gravity's Rainbow will do the same thing for five times as long, and you have saved yourself a season.
The path opens with Slow Learner, Pynchon's collected early stories. Its value is almost entirely the introduction, in which he takes his own juvenilia apart with real severity and tells you what he had been reading and getting wrong. Read the introduction; treat the stories as optional.
What the novel costs
Gravity's Rainbow has no chapter numbers, roughly four hundred named characters, no stable protagonist after the first third, and a habit of dissolving a scene into song, film pastiche or a limerick. The first two hundred pages are the wall. No trick makes them easy. What helps is knowing that the disorientation is engineered, and that the book does not settle into conventional shape later on.
Two histories do more to make it legible than any literary criticism. The Rocket and the Reich is Michael Neufeld's scholarly account of Peenemünde, the V-2 programme and the slave labour at the Mittelwerk, the underground factory Pynchon sends his characters into. Operation paperclip, Annie Jacobsen's account of the American recruitment of German rocket scientists after 1945, covers the historical afterlife the novel treats as its real subject; historians have argued with it on points of interpretation, so read it as narrative rather than settled record.
Rilke matters too. Duino Elegies is quoted, misquoted and parodied all through the novel — the angel that is terrifying, the arc that rises and falls. Read the elegies once straight through beforehand and you will hear them.
The apparatus, and how to use it
Roughly half this path is not reading but equipment, and equipment is used differently from books.
A Gravity's rainbow companion, Steven Weisenburger's page-by-page annotation, is the indispensable tool. You do not read it through. You keep it open beside the novel and consult it when a German phrase, a chemical process or a 1944 dance tune stops you. Weisenburger keys his entries to page numbers in specific editions, so check that the edition you buy matches the one his companion indexes, or the whole thing misaligns.
A Reader's Guide to Gravity's Rainbow is Douglas Fowler's older and lighter version of the same job: less exhaustive, more interpretive, and readable cover to cover before you begin if you want a map rather than a lookup table.
The Cambridge companion to Thomas Pynchon is a collection of critical essays spanning the whole career. Read its chapter on this novel early if you like, and save the rest for afterwards. Gravity's Rainbow, Domination, and Freedom, by Luc Herman and Steven Weisenburger, is a study of the novel's politics and composition drawing on the surviving typescript; it is the most specialised item here and belongs after you have finished, not before.
Where to stop
Abandoning Gravity's Rainbow is a respectable and common outcome. If you enjoyed The Crying of Lot 49 and two hundred pages of the big novel are still pure friction, the honest options are to switch to Mason & Dixon, which is warmer and more human, or to stop. Neither is failure. Some readers return to this book for decades and others never finish it, and the difference is not intelligence.
Readers who arrive here from other difficult modernist novels usually want Ulysses next; the preparation problem is the same shape.
Follow the full ordered path here: What to Read Before Gravity's Rainbow: The Pynchon On-Ramp, in Order.