First, you have to finish writing your manuscript! If you think of getting your book published as kind of like getting a new job, then your manuscript is your resume.
It’s very rare for a publisher to accept an unfinished manuscript for publication. There are exceptions, of course – some non-fiction publishers will solicit manuscripts from known writers whose work performs well or who have other popular products or services. For most writers, though, you need to have a completed manuscript that (preferably) has been edited so you’re presenting your best work. Some writers use the services of “beta readers” (people usually outside your immediate circle of awesome people who will read your manuscript and give you pointers, not necessarily on things like typos and grammatical oopsies, but on bigger things that could be problematic, like places where they get confused, or where the narrative shifts, or where your data doesn’t add up). Many will use the services of freelance editors or manuscript evaluation services (like those offered by the Saskatchewan Writers Guild) to go over their manuscripts before submitting them.
It’s generally good advice to do a little bit of research when you’re ready to submit a manuscript to a publisher. Go to your local library and find books similar in theme or genre to yours, and make a list of the publishers whose books you like. Publishers have areas of focus or genres they prefer to work with. Some publishers won’t accept unsolicited manuscripts (that means they aren’t interested in reading a manuscript if they haven’t asked you to submit it first). Some publishers have a mandate to produce the work of local writers. So do a little bit of homework and find out who publishes the kind of book you’d like to see your name on. Some writers submit their work to literary or genre magazines and contests so they can build up a kind of “publishing resume”.
When you have that list in hand, check out publishers’ websites or get in touch with them. Find out if they accept unsolicited manuscripts, and if they do, what format they wish to see your manuscript in. Most publishers will have this information posted on their website. Some publishers only accept manuscript submissions during certain parts of the year, or they entertain submissions of a certain theme for a special project they’re working on. Be mindful that most small and regional publishers produce a dozen or more titles every year, and they may simply not have the capacity to accept your manuscript currently.
Also, you may wish to ask the publisher what their production timeline is – it’s unusual to see a book go from manuscript to the shelf in less than a year, unless you’re working with a hybrid publisher or a vanity press. Some publishers may have that kind of turnaround time, but most do not. Your book will need to go through production (including the editorial process, the design process, and the proofreading process, during all of which the publisher is mindful of marketing decisions as well as promotion and distribution). It takes time to do things right.
If your manuscript is selected for publishing, congratulations! A publisher’s very first marketing decision is in whether to publish a book at all! Make sure you understand the terms of the publisher’s contract, including your job in marketing the book and your royalties. Some publishers include the writer as much as they can through the entire production process, while other publishers do not. You may be shown suggestions for cover art, or you may not be. Ultimately, your publisher has a good handle on what performs well in the marketplace and what sorts of things give their books a ‘hand up’ in the highly competitive book industry. The relationship you have with your publisher is a business partnership – if you have questions, don’t be afraid to ask. You guys are in this together!