The most important things to consider when choosing a book to read are the name, the summary on the back, and the length. The name of the book should grab your attention. The summary will give you insight on what the books holds, to see if you're interested in reading it or not. The length of the book is important to consider, because you need to decide whether or not you're willing to read that much/that little about whatever the book is about.
hope this helps!