One of the "easiest" types of readers' advisory questions we get is when a customer walks up and says they've read a book by an author and they want more by that author. If you're especially lucky in the moment, it will be an author with a long backlist and you can immediately satisfy your customer's needs. That is until you hit the jumping genres books. What happens when they've read all of John Grisham's thrillers? Do you propose A Painted House, which is not a thriller at all? Or his true crime study of a man on death row, The Innocent Man? What if they're reading Anne Perry, would you suggest her fantasy novel Tathea?
There are many authors who write something out of their normal range, so to speak, ranging from romance authors Julie Garwood and Christina Dodd who have moved into romantic suspense and paranormal romance respectively, to John Banville and his turn as a mystery author. Can you comfortably suggest those to a customer who wants to read an author's next work? Even more problematic, what if the book they've read is the one that's a departure for the author? If your customer has just read Christine Falls by Benjamin Black and is dying (no pun intended) to read more by the author, should you suggest The Sea? Or James Patterson's change of pace, Suzanne's Diary for Nicholas - would that be a match for fans of his thrillers? Suzanne appeals to readers of Nicholas Sparks and Richard Paul Evans — but his serial killer thrillers, not so much.
Now that I've posed all these questions, I don't know that I have an answer for you. Some of the moves authors have made make for easy answers. Unless the person standing in front of you is a die-hard Anne Perry fan, chances are they aren't going to want to read her fantasy novel. And if they've read the Black/Banville mystery because they're a mystery reader, then The Sea wouldn't be the first thing I'd suggest. That's not to say you can't challenge your readers or help them stretch, but I don't see this as my primary goal when a reader is looking for that next book.
Your job gets even more complicated when the jump an author has made is subtler. A reader who adores all of Julie Garwood's historical romances may or may not want to make the shift to read her romantic suspense novels. On first glance, it seems like a no-brainer. They're all romances, after all. Why wouldn't a fan want to follow along the way? In Garwood's case, the reasons are many. With her newer incarnation, the romance takes a back seat to the suspense, the violence level has risen, and Garwood's voice has changed. Speculative fiction author Elizabeth Moon has written both fantasies and science fiction. Would I suggest both types to a reader? It depends.
Though there are no hard and fast answers in this essay — or in readers' advisory for that matter — I do have a suggestion for when you get that question from a reader for the next book by a favorite author. If you're not familiar with the author or only know some of their work, then try to take a little time during the transaction to scan the book (either digitally or physically) and learn more about its genre and subgenre.
Scanning digitally includes making note of where the book is shelved and any descriptive material your catalog can provide. Physically means just that. Cover art is a big indicator. A mystery reader probably won't want the book with the dragon on the cover. And blurbs, though occasionally misleading, can be helpful. Additionally try to glance at who's quoted. If the authors quoted are other mystery, science fiction, romance, etc, they give you a pretty good indication of the contents and whether they'll match your reader's tastes. Finally, if your library subscribes to a great database like Reader's Advisor Online, a simple title search provides detailed information on a book's genre and subgenre. This can be extremely helpful when trying to determine whether a book by the same author is a read-alike.
Sounds so basic, and yet… Like everything else we do it means we need to take a little extra time. Is it a fatal error if they get a book they don't like? Probably not, but because the RA relationship is a fragile one, it's one I'd like to avoid whenever possible.

Jane Jorgenson is the Home Services Coordinator at Madison Public Library and an instructor for the distance education program at the University of Wisconsin-SLIS. She also acts as an editor for Madison's book reviews blog, MADreads (http://www.madisonpubliclibrary.org/madreads).