Format Your Manuscript Properly
Type your manuscript according to common manuscript-formatting guidelines. A final manuscript should be neatly typewritten in black ink on plain white paper, double spaced, paragraphs left justified, with a standard five-space indent at the beginning of each paragraph and printed in an easy-to-read font. Each page of the manuscript should be identified with a brief header--part of your book title, a slash mark and then your last name--and be numbered. Use 1-inch margins on all sides.
Include a title page with your manuscript. This should be a page all its own with the title of your manuscript typed and centered about one third of the way down on the page. Double space and type your name (as the author) or the pen name you wish to use, also centered. At the bottom right-hand corner of the title page, type your name, mailing address, phone number, e-mail address and any other contact information--single spaced and right justified.
Include page breaks in your manuscript so that each chapter starts on a new page. Type the chapter title or chapter number about one third of the way down on the page, either left justified or centered. Then double space and begin typing the chapter text.
Proofread your manuscript thoroughly. Then consider having an impartial third party you trust proofread your manuscript for you. Make any corrections necessary. You want your manuscript to be the very best it can be before you send it to an editor for consideration.
Prepare Your Cover Letter
Find out the name of the current editor or editors at the publishing house to whom you want to submit your manuscript. Consult the current edition of the "Writer's Market" or other source book for this information, look online or call the publishing house. Verify the current address of the publishing house as well. Editors at publishing houses change frequently and you want to be sure you have the right information.
Type a professional cover letter to accompany your manuscript. Just like your manuscript, your cover letter should be neatly typewritten and contain your contact information. It should be addressed to the proper editor--and be sure you spell the name right--at the publisher's current address. The cover letter can be left justified, single spaced with double spaces between paragraphs and should usually be only one or two pages long.
Entice the editor to read your manuscript. In the first paragraph of your cover letter, use a hook or lead to capture the editor's interest and make him want to read your work. Use this paragraph as a sales pitch and focus it on the strengths of you as an author (perhaps you've already published several books or you are a well-known expert in this area), any endorsements you've already received (perhaps from someone famous) or the story itself--whichever will be the most compelling to an editor.
Include a one- or two-paragraph synopsis of your story. Hit on the highlights of the story, the protagonist and antagonist, the major conflicts and resolutions in the story and tell how it ends. Don't withhold anything from the editor, but don't go into too much detail here. Keep it short and sweet, but make the editor want to read the actual story.
Tell the editor why you are qualified to write the book. Sell yourself in this paragraph. If you don't have a lot of previous writing experience, briefly write about how much you love to read other books in this particular genre. Name a favorite author or two and reference something about one or two of their titles that may be similar to how your story is written, the setting for your story or any other factor that seems relevant and interesting. Keep it interesting, but brief.
Wrap up your letter with a few formal details. Tell the editor you are enclosing your manuscript, give a word count for the manuscript and ask the editor to kindly review and consider your manuscript and then respond to you via the self-addressed stamped envelope you are enclosing. Drop down a few lines and type your name. Then sign the letter in ink above your typewritten name.
Present a Professional Package
Keep your manuscript together. Put a rubber band around the pages of your manuscript or use a large clamp-type paper clip to keep the manuscript pages from scattering everywhere if it gets dropped. Do not bind your manuscript in any way. This is considered unprofessional.
Prepare your envelopes. Address a large envelope to the publisher. Be sure you have the correct address and the envelope is large enough to hold your manuscript without tearing. Get another standard business-size envelope, address it to yourself and put first class postage on the envelope so the editor can quickly and easily respond to you after reading your manuscript. This one will be your self-addressed stamped envelope (SASE).
Assemble your package. Place the SASE on top of the manuscript and place the signed cover letter on top of that. Slide the stack into the large envelope and seal it well. Take the package to the post office to have it weighed and affix the proper postage to the envelope. Then mail it out.