One of the fastest ways to sell books is public speaking. What's great about speaking publicly is that you see the results immediately. You speak to a small group of people, could be as few as 10 or 20 people and immediately afterward you sell your book in the back of the room.
To begin with you must know who your target market is because generally if your book is about Biology you stand a better chance at selling books to biologist than basketball players but not necessarily because many people will buy your book because they want your autograph. They may never even read your book but they want to brag to their friends that they met "a real author".
But how do you set up a public speaking event? I say, why waste your time setting up an event from scratch when there are many groups that are begging for speakers to speak to their people and they've already lined up the people. A great organization to start with is are Rotary Clubs. You can google them and find the local chapters in your area. They're a wonderful organization of business owners that join together to network and more importantly do charitable work in their communities. They're always looking for speakers and if you can tailor your book's message to fit their needs they would love to have you speak.
You begin with a simple short email to them introducing yourself to them and what your message will be. They will usually respond within a few days and you find out what day(s) they have available. You arrive early, introduce yourself to the moderator who booked you, be friendly to all the people as they enter and set your stack of books up at a table that is strategically placed right next to the door so that after you speak they HAVE to pass by you in order to speak.
You give a short speech that inspires them and keep it at about 15-20 minutes and allow for questions and answers. Then, afterward you speak.
I suggest you let the Rotary Club members know how much you normally charge and what kind of discount you're offering them and if a portion of your proceeds are supporting a charity even better. Remember to also mention to them that your book would make " a great gift" and that you'll autograph it for them. You'll be surprised at what a positive response you'll get. In my experience at least 50% of the people I speak to end up buying the book. It's an instant way to sell more books and see the results immediately.