There are a lot of very good books about how to write fiction that sells, among them Don Maass's outstsanding Writing the Breakout Novel, Scott Meredith's classic Writing to Sell (out of print but well worth searching out a used copy) and The First Five Pages by Noah Lukeman.
There are also a lot of great books about how to put together a non-fiction proposal for everything from prescriptive diet books to serious history, books like Susan Rabiner's excellent Thinking Like Your Editor.
But what about narrative non-fiction, ie, non-fiction that reads like a novel? Books like Into Thin Air by Jon Krakauer, A Perfect Storm by Sebastian Junger or The Rape of Nanking by the late Iris Chang are all great examples of non-fiction that reads like a novel, a true story with prose so compelling that you simply cannot stop yourself from turning the pages to find out what happens next.
Well, I have some good news for you narrative non-fiction writers: The Elements of Narrative Nonfiction: How to Write & Sell the Novel of True Events by my FinePrint colleague Peter Rubie has just been released by Quill Driver Books. Originally published by Harper Collins in the early 90s as Telling the Story, Peter has extensively revised and expanded the book to include case histories of some of today's bestselling narrative non-fiction titles, as well as plenty of hands-on advice and sample non-fiction proposals. Worth checking out!