Allow me to share some of the tips the sources above have given, mixed with a few ideas and thoughts of my own.
Promote Your Book Yourself
Before authors promote a book, they should promote themselves. Of course, if a writer hasn't promoted herself yet, doing so can occur after the book, but promotion should first be about the author.
Often writers wait too late to promote themselves. Joan Steward says authors should become "experts" and build a personal base before promoting a book. Nonfiction writers have a built-in topic about which to write articles or present workshops: the theme or sub-themes of the future nonfiction book. However, fiction writers can also be experts, if they have researched information for their books correctly. For example, research for a book dealing with kidnapped children can create an author who is an expert on the aftereffects of being kidnapped on the children and families; what steps to take to find kidnapped children; or how to survive being kidnapped or having a child kidnapped.
Authors who have studied and developed their own writing expertise can share their knowledge of writing and become an expert on writing. But, that expert level should probably come after proving through being published that they know the subject. To gain more knowledge about writing, a person can attend classes, workshops, and conferences about writing. He/she can read articles and books about writing, keeping the knowledge that usable and deleting the rest.
Another way authors can promote themselves and create themselves as experts is to create cheat sheets and checklists. Joan Stewart, the Publicity Hound, states the following: "Readers love chunks of information they can digest easily in just a minute or two. That's why they're wild about cheat sheets and checklists. These powerful one-page PDFs are like digital crow bars that can pry an email address out of a website visitor faster than any other lead magnet you might offer." She goes on to say:
Checklist/cheat sheets can be released before the book for promotion or used in a the appendix of a book or both. These lists don’t have to be about serious topics. Be helpful and have fun.
1. Create a checklist of advice from your main character on how to overcome a challenge or solve a problem mentioned in the book.
2. Offer a cheat sheet for tourists who want to visit the city, state, region or country where your novel takes place. If your book is about Venice, your cheat sheet could be titled, “Favorite Foodie Hideaways to Explore in Venice.”
3. Do your sci-fi characters have their own language? Create a cheat sheet of words and their definitions.
4. Create a checklist of “7 Most Romantic Places to Propose” that ties into your romance novel.
5. Does your children’s book include a fairy as one of the main characters? Create a cheat sheet of “What the 5 Most Famous Fairies Can Teach Your Child.” (The Tooth Fairy, Tinkerbell, etc.)
Include a short blurb about your book at the end, with a link to the sales page.
Writers need to become familiar names on social media, familiar in a good way. They can post encouraging comments on other people's blogs, social media posts, etc. They can post reviews of other authors' books on their blogs and the other authors' blogs. Posting bits of information on Facebook, Twitter, Google +, and other media helps to build interest in the writer and in his/her topic. The more readers are interested in a writer as a person, the more they will be interested in reading the writer's book.
I hope to share more tips about promoting and marketing in the future.