I get asked this a lot. Here's what I usually say.
Consider self-publishing. Agents and publishers are hard to get, especially for first-time authors (unless you've got a big name and a big following). Plus, things are changing in publishing, with all kinds of innovative and affordable opportunities (e-books, print on demand, etc), and new ways of self-publishing which cut out middlemen (like agents and publishers). So, first, I would not rule out a form of self-publishing. I recommend it to people who do not want to wait the year or three or five or ten it might take to send out queries to agents and find one to take you who then sends the book out to editors, and then there's still the whole publishing process to go through. Also, if you are absolutely married to your title and every word in the book, and are firm on the cover design: you will have to let go of all this if you go with a traditional publisher.
Self-pubbing is a good option if you have a niche with a built-in following. If you're a yoga teacher and you write a book on wellness, you can promote and sell it at classes and events. My neighbor Terry Church, who studied with the original horse whisperer Tom Dorrance, travels around the country teaching horses and riders how to understand each other. She wrote an autobiographical novel about her journey and philosophy, and Finding Pegasus has a built-in audience of her students and colleagues in the horsey world.
Then again, maybe not. One downside of self-publishing is distribution; without a publicist and a distributor, it's up to you to get your book known and into bookstores and libraries--not an easy thing to do, especially outside of your local area. Again, that's why having a built-in audience helps with the selling part of self-pubbing. Like publishing, publicizing is also evolving, with new venues (what's a Book Blog Tour?), and you can DIY or hire an independent publicist to help you gain access. You may think publicists are just sweet-talkers, but they have access to reviewers and bloggers and broadcasters precisely because they've spent their careers sending these newsmakers appropriate books, authors, and story ideas. The publicists have access because they've earned it and don't misuse it.
Also helpful: having realistic goals. Please don't tell me your goal is to get rich and or famous from your book, because these outcomes are mostly controlled by luck, pop culture trends, and other forces out of your control. Publishing a memoir to preserve your stories of escaping from Nazi Germany and landing in Lansing, so your friends, family, and the local historical society can hold onto them--now that's a goal you can influence. And realistically, that's a couple hundred copies, distributed locally.
Also, I'm not going to lie to you, some venues are not open to self-published books: reviews in most magazines and newspapers, for instance. And some people, including me, still have a bias against self-pubbed books. We see editors and agents as gatekeepers who provide a service for readers. Traditionally published books have beat out others, then been edited and edited again, so we trust that they will, for the most part, be readable and interesting and maybe even important, with an easy-on-the eyes lay-out and only one or two typos. Exceptions abound (Fifty Shades of whatever, Bridges Over you-know-what), but with a self-pubbed book, it's more of a crap shoot. For better and for worse, anyone can now write and publish a book. Many of us like to hedge our bets with books that have gone through a tried-and-true vetting process
The plan. Maybe you want to try the traditional route, to test your patience and see how your book is received. If you get antsy with one rejection after another (very common; I got almost 30 rejections on my memoir before getting a publisher), and don't want to do another rewrite (even though, as in my case, the editors are probably right and those changes they suggest will improve the book), then you may want to start investigating self-pub options--and there are lots of them.
Just one thing. Promise me you won't mortgage the house to print up three thousand, or even one thousand, copies of your book. That's a ton of books to sell, or even give away. And you can't lose the house because you need the garage to store all those books you can't get rid of.
Next question, How do I get an agent? Coming soon...