Write blog posts: You can look into the possibility of guest blogging. Find blogs that other people have started and ask if they would like you to write a few blog posts for them. At the end of each article you can write a short bio on yourself where you mention the book.
Appear at at book fair: Find out if there's a suitable book fair and try to sell some books there. Perhaps you find people there who are not just interested in buying a personal copy of your book, but also are willing to promote the book for you.
Contact local media and ask the if they can interview you about the book. A lot of their readers, viewers or listeners may be interested in fiction - and if your book is about a burning topic, they will very likely ask you to come and talk to them. If it's a newspaper, perhaps you can place an ad with them too.
Create a yearly event that has to do with the content of your book. Find out if you can arrange something together with other writers who work on the same topic.
Get work as a speaker: Find out if anyone is interested in having you as a guest where you speak about your book. Bring a few copies and try to sell them.
Send out e-mail: While you're researching for your book you're very likely to interview people and get in contact with others who would be interested in reading your book. Save the names and addresses and when the book is finished you can send them an e-mail to let them know.
Sign books: Book signing is a well known type of event that's often held at the bookstore where they market your book. Ask the book store what they do in order to arrange book signings. Let them know that you're interested in coming for an event. They will probably ask you to speak about the book and then give buyers the opportunity to have their copies signed.
Meet with a book reading group: Find out if there are book reading groups that would be interested in having you come to one of their meetings. The members are usually interested in the authors of the books that that they read - and perhaps authors in general. They want to know why you wrote the book and what it's about. Pick out a section of the text and send it to them in advance.
Start Social Media on your book: When people ask you about your book, you can send them there to pick up information. You can also work on other social media and let people know that they can reach you there, such as on Twitter, Instagram, Facebook etc.
Alas, you will find out that everyone is interested in an author - in You. However, you need to share your story and your experience. Talk people and interact with them.