Most people believe that writing is the hardest part; once their book is published, they think, it will fly off the shelves. The reality is that they will be lucky if their book even gets any shelf life. The most important lesson that an author can learn is that the work doesn't stop after you've turned in the manuscript. That's when the hardest work begins.
If you want your book to be bought and read by the widest possible audience, you have to start marketing it long before its publication date. Here are some simple tips on marketing that every author should take to heart:
1. Website: There are services that allow you to host and build your own website for free -- or you might want to invest in a web developer, who will choose one for you. But once you've settled on your book's title, go to a domain name service and buy the url (consult with your web developer, if you hire one, about where to go. GoDaddy and Network Solutions are two of the most popular. Buy a few other urls that are similar and redirect them to the preferred domain name. Document your purchase well and keep track of credentials. Allow the registrar to auto-renew on your behalf.
Then you'll need to build a book website. If you don't hire a pro to design it, there are CMS providers (like WordPress) that enable you to do it yourself fairly easily from templates. Make sure it includes a piquant and highly quotable summary (this is important, because it's the only thing many reviewers may read), a downloadable high-resolution image of the book cover, and a flattering author portrait. Also be sure to include tabs for media profiles, blurbs and advance praise, and a multimedia showcase for broadcast and radio interviews, press clips, and photos.
2. Social Media: Facebook will be a powerful tool. Decide well in advance whether you want to market the book using your existing profile or if you'd rather create a book fan page that's open to a wider audience. If the latter, start early so you can get a lot of fans. Make sure you keep your page lively and refreshed with new and appropriate content.
Twitter and Instagram are important too. Open an account, start following authors, book stores, book clubs, and public figures who appeal to the same audience as your book will, and Tweet often, including a link to your book's website. Share Instagram photos and promote those talking, tweeting, Instagramming the book.
3. Presales: Encourage friends and family to place their orders several months prior to the onsale date, when the book is still in production. Any early movement will help create a buzz and Amazon may start to take note. Your Amazon rank (located in the book details section) will give insiders a peek at how your book is performing.
4. Create an Amazon Author Page: Upload up to five photos, include bio information and links to your website and Twitter account. If you have a blog, link to that as well -- your new posts will appear on the page.
5. Book Trailer: A book trailer is a great visual way to tell potential readers about your book in about two to four minutes.You don't need a major production company to put one together. Use your own images or stockshots or video that you can source at places like istockphot.com, shutterstock.com, flickr.com or bigstockphoto.com. Piece together the message using words across the screen, the fewer the better. Add a backdrop of music. You can find almost any kind of music for purchase at 300monks.com, which is searchable by mood, genre, or key word. Once your trailer is ready, share it widely via social media -- and be sure to link it to the book's pre-sale page. Ask your publisher to upload it to Amazon, B&N, and other retailer's book pages.
6. Promotions and Contests - ask your publisher to run a contest for a free signed copy of the book to create awareness and buzz. 
7. Make a Mailing List - and Use It: Start gathering a mailing list so you can share news and information, media releases, news clips, features, etc. via email. 
8. Make a media list - and Use It: Start compiling a media list. Think about your book's audience -- whether it's people with an interest in politics, science, religion, business, tech, entrepreneurship, lifestyle, design, health, etc. -- and then target the kinds of media who would be the most interested in featuring you or the book. Don't just stick with book reviewers.
Rather than annoy the wrong people with a general blast, be sure to tailor your pitch to the appropriate media. Give them a story; feel free to suggest an entire segment. A boilerplate press release will not work. Producers want to know how this will help their viewers and readers. Package the story.
9. Excerpts and Feature Articles: Start writing feature articles and adapting excerpts from your book and submit them to as many print and on-line venues as you can. Try to have news and seasonal hooks if possible.
10. Book Party: If you're lucky to have friends or family who offer to host a book launch event, that's great. But don't bother celebrating if you can't get media attention for it. It's a nice thing to do, but it's a waste of time, money and resources that could have been better spent on publicity efforts.
Here are some great tips on how to host a book launch event that will actually help you sell your book:
Creative Ideas for a Book Launch Party
Photo credit: Mark Luciani and George Pimentel
Watch Upgrade Your Book Launch for more tips: