With non-fiction books, you can query agents and publishers with a book proposal (if you plan to go the traditional route). In other words, you can send out query letters while you are writing the book. However, this practice is not acceptable with a novel. The story has to be complete before the querying process can begin. Writing a query letter and a book proposal is not a simple task and is quite different from doing this for a novel. The recipe on how to write non-fiction queries and proposals will vary substantially depending on what type of non-fiction book you are writing.
Today, an author has a number of options on his the book gets published. Not so long ago, an author’s only recourse to get published was to convince an agent to represent the book. Those days are long gone. Now an author has a number of paths to publication.
A brief description of each is listed below.
This option is the dream of almost all authors in the beginning. Many of these publishers require an agent to submit. While desirable, this option can take years to publish the book if successful.
There are many of these publishers and they are generally easier to link up with. Most of them don't require an agent and they are much faster to publish than the big guys.
These publishers will accept your book without question provided you can afford to pay their fees. The fees are enormous. Think thousands of dollars. The publisher will also attempt to convince you to enroll in quite expensive marketing programs.
These are relatively new. While they have some legitimate features such as editing services and cover production, other services are similar to vanity presses in that the author pays the publisher to publish the book. This maybe a viable option for you if you can’t find an agent and don’t want to self-publish your book.
This option is increasingly popular with authors. With this option, the author has to do all the work a publisher would do.
Be warned: Writing a book does nothing to prepare you for the tasks associated with self-publishing. It is arduous and expensive.
Still, thousands of authors do it, so why can't you?