I published my own nonfiction book, and now I’d like to query commercial publishers about a second edition, but how can I approach them about this idea?

from The Beginning Writer's Answer Book, edited by Jane Friedman

There are two ways you can approach this. One way is to submit a copy of your book to several publishers along with a concise description, its market potential, and the sales record you achieved on your own. Include any other information likely to convince them to invest in your project (such as your marketing plan), as well as copies of notable reviews and special promotional contacts you may have. If your book didn’t sell many copies, and you consider your self-publishing attempt a big mistake, then don’t send a copy of the book. Query the publisher as if it were a new project, and if your manuscript is requested, send a print-out of the word-processed manuscript (not the typeset book)—as well as the proposal.