Enter the title of a book, its author or its International Standard Book Number at What Should I Read Next? to find similar books. If you aren't satisfied with this site's suggestions, simply click on one of the book's tags to find more books that share the same tag.
There are additional websites you can use to find reading suggestions. For example, Goodreads lets users create reading lists for other people's viewing. As a result, if you search for a book using the Goodreads database, you can usually find reading lists filled with similar books. Alternatively, if you know a Goodreads user who shares your taste in books, check his reading list from time to time for more reading suggestions.
Another tool for obtaining reading suggestions is Whichbook, which offers reading lists and a useful search service you can operate with a number of sliders. By adjusting these sliders, you can get reading suggestions with the same sort of content as your favorite books. For example, if your favorite book is positive and uplifting, you can adjust the slider from Bleak to Optimistic. In total, there are 12 sliders, with examples ranging from Happy and Sad to Funny and Serious.