First Things First
The fundamentals for all query letters stay pretty much the same, despite the category. Your nonfiction proposal should be ready before you start querying agents. A good technique is to read your proposal, pull out the three to five most persuasive points, and make them the core of your query presentation. You need to start with a “hook” to grab the agent or editor’s attention, work in the reasons for your book and why you should write it, and, ultimately, leave him asking for more.