Excuse me while I once again deliver myself of the opinion that Diana Wynne Jones is the Greatest Living Author in the English Language.
If you prefer satire, start with Archer's Goon. If you prefer romantic comedy, start with Howl's Moving Castle. If you like epic fantasy, start with The Homeward Bounders. If you hate epic fantasy as it is mass-marketed, start with The Tough Guide to Fantasyland. If you prefer domestic horror, start with Aunt Maria or Time of the Ghost. If you prefer domestic fantasy, The Ogre Downstairs, Wilkins's Tooth, Who Got Rid of Angus Flint?, or Power of Three. If you like elaborate worldbuilding, the Dalemark Quartet - The Spellcoats, Cart and Cwidder, Drowned Ammet, and Crown of Dalemark. If you like worlds dashed off as casually as sandwiches in the world's best deli, Deep Secrets and The Merlin Conspiracy, or the Chrestomanci books, but those are (by her standards) deeply flawed, so you won't know what I'm raving about just yet.
Once you're hooked, you'll happily read her grocery list if you can find it, sure that by the time you reach the toothpaste you'll have learned that it wasn't just a grocery list...