He can basically be broken down into his non-fiction collections, his short fiction collections and his novels. Personally, I would start with his non-fiction (Consider the lobster, supposedly fun thing). Then maybe some of his short fiction, like Brief Interviews, which can be a little more experimental, before tackling the novels.
It's a discussion of descriptivist vs prescriptivist grammar and led me to A Dictionary of Modern American Usage, which is a way more fascinating book than its title would imply.
This has been my path through his work, and it's been pretty enjoyable to follow. The non-fiction is definitely the most accessible, and built my taste for his writing.
