Don't send out a dozen form letters. Send a personalized proposal, along with a few details about your own expertise and writing experience, plus a self-addressed stamped envelope. Keep in mind that the key element here is to avoid wasting your time and that of the editor. And don't be offended if someone is not interested. Publishers tend to be very specific in their tastes.
Most editors expect to hear from writers with some sort of track record.
For example, if someone submits a short-story collection to a publisher without ever having gone the route of submitting individual stories to the many literary magazines, and finding some initial publication, youre not going to find success with the book publisher Before submitting any manuscript, it should be as polished as possible. This means several rewrites and major proofreading. A title page should be included with your name, address, phone number, word count and rights being offered. Each page of the manuscript should have the author's last name in the upper left corner and the page number in the upper right. Pages should be submitted unbound and mailed in a sturdy padded envelope or box.