Research publishing companies or editors to contact. Focus on the editors that will be most interested in your book, or have the most need for your subject matter. The small and mid-sized publishing houses tend to have a limited focus. The larger publishing houses have many divisions with editors specializing in one area.
Send query letters to publishers or editors. Use an up-to-date directory to find the names of specific editors you think would be right for your material. Do not send general queries. You can send the query letter by regular mail, or email, if available. It should be a brief introduction of yourself that includes the genre, word count and "hook" of your book.
Send follow-up materials once an editor has expressed interest in your book. If your book is fiction, send a brief synopsis of your story and up to three sample chapters. If your book is non-fiction, send a proposal packet that includes a table of contents, overview of the book, chapter outline, up to three sample chapters, your biography and marketing plan.