Make sure your manuscript is book length. Typically, this means it has to be more than 25,000 words, though some publishers don't consider a manuscript book length unless it is over 50,000 words, which translates to about 160 pages. If your work is shorter, you'll have to pursue a publisher that specializes in novellas or other forms of short fiction. There is no limit to how long a novel, memoir or other standard-form book can be, but for purposes of marketing and logistics, publishers tend to prefer manuscripts that are less than 100,000 words, particularly if they are written by young, debut writers, who typically constitute a greater commercial risk than an established brand-name author. Different standards also apply for books of poetry, artwork, photographs or other specialty productions that are accepted by niche publications. Before offering any work to commercial firms, be sure to familiarize yourself with their submission guidelines and the authors and kinds of books they've published in the past.
Review and self-edit your work carefully. Then, have your friends, parents or other people you can trust read the book and give their honest opinion of it. Try to emotionally separate yourself from the book, and listen to the compliments and criticisms with a neutral ear, as these comments are representative of the response you'll get from the reading public. Once you're satisfied that the book is as good as it can possibly be, consider hiring a freelance editor to give it a final check through. These editors usually charge by the hour or by the number of words in your manuscript. It's preferable to be charged by word count, since that way, you'll know your costs up front. Consider looking for editors on work-for-hire websites such as Elance or Odesk, or search for them via organizations such as the Northwest Independent Editors Guild or the Writers-Editors Network. Make sure to avoid working with anyone who wants to be paid entirely up front. Fifty percent up front and 50 percent upon completion is the most common payment arrangement.
Attract the interest of a literary agent or editor. This is the most common way writers of all ages get their works published. It is also very difficult, mainly because you have thousands of writers trying to get the attention of only a small number of agents and editors. Make sure that any agent or editor you solicit specializes in the field or genre that your book is in. Consider submitting your manuscript to editors who've published books you like or agents who represent authors you admire. For the most part, you'll have to focus on literary agents, since fewer and fewer editors are accepting unsolicited queries anymore. There are still a few editors, mostly at smaller, more specialized publishing houses, who accept unagented submissions, but they are more the exception than the rule. Since you're a minor, you will have to have one of your parents or legal guardians sign any contracts offered to you.
Self-publish. If you either can't attract the interest of a literary agent or editor or you want to exercise exclusive control over your book's production and distribution, self-publish and sell the book yourself. The most inexpensive way to self-publish is to utilize the services of a print-on-demand specialist, or print broker, who will assign your book an ISBN, ensure the layout is correct for printing and then produce however many books you order. If you want to take a more hands-on approach, you could form a small publishing imprint and purchase a block of ISBNs yourself. The smallest block of ISBNs available for purchase is 10 for $250. You would then have to work directly with a printer to typeset and produce your book. This printer could either specialize in short-run print-on-demand or be a more traditional offset printer, specializing in print runs of 200 units or more. The more books you print, the cheaper the unit cost, but the more costly and potentially difficult it will be to transport and store the larger inventory.
Market your book. No matter how you manage to get your book in print, you won't be able to sell any copies unless you aggressively market it. Even if a mainstream publisher buys the publishing rights to your book, many will still expect you to take a proactive role in making potential buyers aware of it, to include maintaining a website and blog, traveling on book tours and doing interviews with print, radio and television personalities.