The first step to publishing a book is knowing what a publisher wants. Every publishing house has a submission style guide for writers to follow, and it is up to you to learn it. Use a publishers listing such as Writers Market to find a publisher that produces books like yours. Pay special attention to the genres a publisher is interested in. A "genre" is a type of story, like science fiction, nonfiction, or mystery. If you send a children's book to a publisher that only publishes adult novels, your manuscript will not even be read.
Format your manuscript according to your target publisher's style guide. Set your margins and spacing as required by the publisher. If certain formatting issues are not addressed by the publisher, follow this most common format: One-inch margins all around; cover page with the genre in the upper left-hand corner; word count in the upper right hand corner; title of the book centered on the page; beneath the title should be a byline with the author's pen name (or real name if you don't use a pen name); centered at the bottom of the page should be the author's real name, address, phone number, and email address.All pages, starting with the second, should have a header with the author's name, title of the book, and genre, and a footer with the date and page number.Start the first page of every chapter one-third of the way down the page. Include a chapter number and title and then skip three spaces.Almost all publishers request double-spacing throughout the entire manuscript. Originally, this was done when writers wrote manuscripts on typewriters. The double spacing allowed the editors to make comments about each line. Today, the double spacing is required simply because it is easier to read (but again, check the publisher's guidelines to make sure).
Have your manuscript professionally edited. This is a step many writers skip because professional editors can be costly ($5 to $15 per page). But the money you put into professional editing could mean the difference between having your manuscript read thoroughly and having it thrown into the slush pile. Publishers want to know that they are working with someone who is serious about writing and someone who is willing to do a little of the footwork. Do not make the mistake of thinking that it is the publishing editor's job to clean up your manuscript. Having a great story idea does not make you a writer. Knowing how to write makes you a writer. Even the most gramatically-skilled writers make mistakes and require the services of outside editing services.
Submit your polished manuscript to your choice publishers, either electronically or by snail mail, depending on their guidelines. Most publishers will ask for a query, which is a one- to two-page letter describing your book and your qualifications as a writer. This letter is required even if you send the entire manuscript. Remember that the query letter is the main selling point of the book. It is the first communication you will have with a publisher, so you need to really sell yourself. Don't go overboard. You want to be perceived as a professional, not a lunatic. Describe your story and how it is different. Talk about your education or background or anything that gives you leverage for this type of book (i.e., you have an English degree or you are a history enthusiast). If you send your query or manuscript via snail mail, include a self-addressed stamped envelope. If you do not include the SASE, you will not get a reply.
Deal with rejection effectively. Even if you have written the most brilliant book, chances are your manuscript will be rejected. Sometimes there does not even seem to be a reason for it. Don't take it personally. Publishers are just like regular people searching through the aisles of a library. There may be some great books there, but they only want one. So they pass the others up in search of the one that's right for them. When you receive a rejection (usually in the form of an impersonal "not right for us" letter), reread your manuscript and see if you can improve it in any way. You'll be surprised at the number of changes that can be made. Gather another list of publishers and send the manuscript out again. Never give up. If you are a true writer deep in your heart, your book will be published.
Don't stop writing. While waiting for your book to be accepted by a publisher, move on to your next book. Don't ever stop writing. If you had one good story in your head, you probably have dozens of others waiting. Follow the above steps for the next book too, and continue writing until you have no stories left inside you.
If all else fails or if it takes too long to get your book published, consider self-publishing. Long ago, self-publishing was considered vanity publishing. That is no longer true. Commercial publishers are just too busy sifting through junk to notice every best-seller. Self-publishing services have become more readily available, making book publishing possible for just about anyone. Lulu is one of the more popular and accommodating services (www.lulu.com) that offers professional printing of your book. They will even do illustrations, design your book cover, and offer editing services at an additional cost. Note that there are a few disadvantages of self-publishing. First is the cost. You have to pay to have copies of your book made. Second, you have to market the book yourself. And third, some of the well-known chain bookstores will not purchase self-published books. This is because they cannot return unsold self-published books like they can with commercial publishers. The upside is that online stores like Amazon.com welcome self-published books. So you can try to sell online first to see how sales go, and then use those sales to convince another publisher.
Don't give up. If there is a true, passionate writer inside of you, your book will be published. Just keep at it. Continue to submit your queries and continue to write. Successful publishing depends on how badly you want it.