WASHINGTON — The advice rarely changes, but book publishers keep cranking it out.

There's always a new crop of people wanting to buy or sell homes, or fix up the ones they have. As long as those folks exist, so will demand for real estate books that tell them what to do and when.

Because the target audience at any time is small, real estate titles make up less than 1 percent of total sales for adult nonfiction books. Nonetheless, there are plenty to choose from — about 32,000 on Amazon.com alone. And there is money to be made on those rare occasions when a real estate book becomes a best-seller.

However, if "best-seller" evokes images of 1 million-plus books flying off the shelves Harry Potter-style, think again. The top-selling real estate book so far this year — "Find It, Fix It, Flip It! Make Millions in Real Estate One House at a Time" — has sold 31,000 copies since January, according to Nielsen BookScan, which tracks publishing industry sales.

So what should you consider when looking for advice about what could be some very expensive decisions? Should you judge a book by its cover? By the star power of its author? By its high-profile placement in the store?

It's easier to make a smart decision if you know a bit about how publishing works.

In every genre, stores stock so-called backlist books — those that are consistent sellers — and frontlist books, those that are newly published and often heavily promoted.

But most real estate books fall in the midlist category, said Scott Mendel, a literary agent in Manhattan, N.Y. They are generally how-to books that come out in paperback with little fanfare, and their authors typically do not command huge advances, all of which makes them relatively cheap for publishers to produce.

"We live in hope that a midlist book becomes a huge bestseller or category killer. When you publish enough books, that can happen, " said Mendel, managing partner of Mendel Media Group. But if the book flops, the financial loss for its publisher is usually minimal.

Many do flop, in part because retailers are an impatient bunch. They give up on books that don't sell quickly, taking them off the shelves a few weeks or months after they debut, said literary agent Alice Fried Martell, of the Martell Agency in New York. Retailers usually send those books back to the publisher for a refund.

"From the retailer's perspective, why take up shelf space with a book that moves slowly when you can replace it with a book that's new and fresh and could be a best-seller?" Martell said. "The window of opportunity to make an impression is very limited."

A major publishing house is most likely to spend money to promote a book if the author has a platform: a television show, a popular Web site or a following that makes the person recognizable.

Case in point: Michael Corbett, author of "Find It, Fix It, Flip It!" Yes, he's a real estate entrepreneur with many years of experience flipping houses. But he's also a one-time soap opera heartthrob (David Kimball on "The Young and the Restless"), as well as a host of the nationally syndicated television news magazine "Extra's Mansions and Millionaires."

Without that kind of platform, trying to sell a real estate book to an agent, a publisher and ultimately a reader can be a real pain, said author Danielle Babb.

Babb sent 300 queries to agents for her first book, "Commissions at Risk." She got two responses, one from the literary agent she now works with. It took that agent three months to find a publisher for her work, Babb said.

Signing other deals became easier after her first book was in print. But Babb said her big break came this year, when RealtyTrac, which operates a Web site with foreclosure listings, agreed to partner with her and promote her most recent book to its 3 million subscribers. In return, the company gets a cut of book sales.

Having access to RealtyTrac's customer base motivated her publisher to put money into promoting her book, "Finding Foreclosures: An Insider's Guide to Cashing In on This Hidden Market."

The publisher hired two public-relations firms, which landed her several television appearances — and voila! "I can now say I have a platform," Babb said. "I signed a new book deal in 24 hours this week. ... For the first time, the advance is making it worth writing the book."

Whether any particular book is worth it to the consumer is another story.

Books sell by word-of-mouth, so it makes sense to start by looking for perennial favorites, said Peter Knapp, marketing director at the publishing firm John Wiley & Sons, which has produced a number of real estate books.

"Those are the books with a strong track record," Knapp said. "If you see a book in its third or fourth edition, you know it's been out there a while and it's been selling well enough that the publisher and author have revised it and the stores want to sell it again. ... And with each update, authors can make improvements."