Back in August I got an ARC of Terry Pratchett's nonfiction book, A Slip of the Keyboard. Pratchett is a British author primarily known for his Discworld series of humorous fantasy books. He's also written some other books like the sci-fi series The Long Earth.
A Slip of the Keyboard compiles articles, letters, and speeches throughout the author's nearly 50 years in the literary industry. Much of the early material especially is of value to writers of any genre, not just those in fantasy. Pratchett discusses a hectic book tour through Australia and has advice for bookstores and authors involved in tours. Even if you aren't a superstar author, there's still some good advice to keep in mind should you ever have a book signing of your own. At the very least it might help you keep in mind what authors go through on these tours when you get annoyed about the author not signing your book.
For fantasy authors especially (looking at Andrew Leon), Pratchett has some interesting views of what fantasy is and should be. As you might expect, he defends the genre from those who think it's just Lord of the Rings or swords and dragons. He credits Wind in the Willows as the first fantasy book he read, but it was LOTR that really got him interested in the genre.
What writers might not like is his tips on writing are more like non-tips. From his writing in this, he seems down-to-Earth about his success and sensible enough to realize that there was no Northwest Passage to finding this success. Basically there's nothing anyone can tell you that can guarantee you success as an author. Learning one author's methodology and duplicating it is not going to make you as successful as that author.
But speaking of methodology, Pratchett is one of those authors who works (or worked) a lot like I do. He used to write 2-3 books a year, which is a slow year for me. He used to use touch typing, before a rare form of Alzheimer's robbed him of that ability, requiring him to use speech-to-text and an assistant instead. He was an early adapter to computers; one of the articles is a review of PDAs from the early 90s. I guess now you understand my point about using the same methodology not guaranteeing success.
More than anything, the nonfiction stories in this help to show you what the life of a successful author is like. As with most authors, it took Pratchett a while to find success. He published his first book with a small publisher at 17 and published some short stories with a local paper that were eventually rewritten and published as The Carpet People. It wasn't until the mid-80s that the Discworld series took off in the UK and Australia. It took far longer for it to catch fire in the US, largely due to publisher incompetence. Pratchett recounts how the US publisher didn't even spell his name right on an early printing of one book! Until about the third Discworld book, Pratchett still had to work a day job, first as a reporter and then as a publicist for a nuclear power plant. So persistence paid off.
The only drawback is that the last quarter of the book (approximately) is mostly articles dealing with Pratchett's Alzheimer's and crusade in support of "assisted death." It's kind of a downer and of course it might not agree with your politics. If it doesn't, you could probably just skip it. The rest I think is a valuable resource for writers and readers of any stripe.
That is all.