If you've written a nonfiction book, chances are you could easily leverage your existing work to create offerings besides your book to enhance your overall profit.
For example, if you wrote a book on the wonders of bananas, why not create an audio program with information from you and other banana experts? Or a banana notebook to catalog experiences with bananas? Or seminars/webinars on bananas? You've already done the research, you already have the seed material - make sure it's working for you! You can sell these items individually, or in packages that make sense together, especially ones that include your book as a feature.
These can be marketed as gift options, or, depending on the price point, a low-value way for someone to test the waters before jumping in.
And these are not only effective for online sales, but can be brought along to speaking engagements, or offered as a promotional give-away.
But what if you're a fiction author? Don't despair - if you've authored a series of books, you have the opportunity to sell a pack of multiples with free shipping or a discount to entice additional sales.
Or, what if a character in the book is obsessed with coffee, what about a coffee mug? Even a temporary tattoo similar to a character in your book - it doesn't have to be a huge effort.
If you authored a children's book, you can bring your characters to life in the form of toys or wall hangings.
Get creative! The more you can bring your book to life, the more likely you are to capture your audience's imagination.