Consult a copy of "Writer's Market" or subscribe to WritersMarket.com on line. "Writer's Market" is a book of publisher listings. It includes a large section of business markets, some that accept a broad range of business books and others that accept business books in specialized categories.
Select a couple of markets that accept the type of business book you want to publish. The listings tell you how to submit, where to submit, what the payment terms will be and whether the publisher accepts simultaneous submissions or previously published material. Note that some publishers will accept complete manuscripts, while others ask for a synopsis and the first few chapters.
Compose a cover letter. Introduce yourself briefly and give an overview of the book and its relevance to the business market, as well as your qualifications for writing it. Let the editor know you're submitting the manuscript for consideration, thank her for her time, and close by stating that you look forward to hearing from her.
Submit your book package, along with the cover letter, according to the publisher's guidelines. Be sure it's addressed to the appropriate party. Try to publish business books in the fall, when many publishers traditionally publish big business books. The beginning of the year is ideal for personal-finance books, when many people think about managing their money for the new year. Summer, when most people are in a recreational frame of mind, is typically not a good month to release business books.
Wait the time specified in the guidelines before you inquire about the status of your book. If the response time isn't indicated in the guidelines, wait about two months before following up.