Okay, let's assume that you're late to the party on this one. Maybe you've seen Fear and Loathing in Las Vegas movie, or you've read bits of Hunter S. Thompson's stuff here and there. You need a heads-up on how to get into the good stuff. Here's what we recommend, in order:
The Great Shark Hunt (1979):
This classic collection of Thompson's work is the gateway drug: it leads to harder stuff. Shark Hunt contains some of his earliest, relatively-straight stories from the mid-'60s as well as his watershed "The Kentucky Derby Is Decadent and Depraved" (one of his first experiments with gonzo journalism) and his first two pieces for Rolling Stone -- including his account of running for sheriff of Aspen, Colorado.
Fear and Loathing in Las Vegas (1971):
Abandon all hope, ye who enter. A hallucinatory account of a journalistic enterprise that went horribly wrong, this book changed journalism, made Hunter a star, and has the power, for a time, to re-orient your perception of the world. The opening paragraph is now one of the most famous in American modern literature; just pick it up, okay?
Hell's Angels (1966):
After the sensory overload of Vegas, you'll be pleasantly surprised by the deep reporting and powerful narrative of Hunter's first book. The riveting subject matter -- the world's most infamous biker gang still on their ascendance -- doesn't hurt either.
Fear and Loathing on the Campaign Trail '72 (1973):
Only Hunter could make theater out of the daily (sometimes hourly) machinations of election-year politics and the whiskey-ripped mayhem of life in the press corps. Especially worth reading this campaign year.
The Proud Highway: Saga of a Desperate Southern Gentleman (The Fear & Loathing Letters, Vol. 1) (1997):
A 683-page smack in the face to anybody who's ever thought of Hunter as some kind of drug-crazed dilettante or one-trick pony, his first volume of letters only gets up to the Hell's Angels period, but it delivers -- brutally, relentlessly, and hilariously.