The most common method is to pick up the book, look at the spine and/or cover title, check the index for a specific item, and then check for the price. I’d like to share a strategy to approach a new title that will enable you to use it more effectively...
Carolyn Barkley offers examples of why the initial approach may not work. She concludes her blog entry with
A thorough examination of a new resource is essential to its effective and efficient use. Consult the title page; don’t rely solely on the information on the spine or cover. Look at the table of contents to understand the organization of the content. Thoroughly read the introduction and/or preface to gain an understanding of the scope of the book as well as find the tips the author may provide about how to best use the resource. Consider the index carefully to understand what is being indexed and how the index entries relate to the text. I guarantee you’ll be able to put the information in the source to much better use.
I wonder if she's a librarian at heart?