Dust jacket

Any information about the author? Is he/she an expert on the subject?
Any reviews of the book?
Any indication of the audience that the book is intended for? Adults, children, academics, students?

Title and subtitle

Does it reflect the information you are looking for? Titles can be misleading.

Contents

Any indication that the book contains the information you are interested in?

Preface

Does the preface indicate that the book will be useful for your topic/work?

Authority

What authority do(es) the writer(s) have on the subject? Are they subject specialists?

Index

Look up all the keywords that describe your topic. Look out for cross references and follow them.

Date of the book

Is the information current or outdated? Is historical information still valid for your topic, or must the information be recent/current?
Even when the book is relatively new you have to bear in mind that it takes quite a long time for a book to be published. The time when the text was completed can be anything between 1 and 5 years before the publishing date of the book.

Definition:
Cross reference
"reference within a text to another part of text" or "refer from one part of something, esp. a book, to another."
(Source: The Collins English Dictionary, 1986:373)