Before you begin to read, consider what types of things you will need to write your book report. First, you will need to get some basic information from the book:

Author
Title
Publisher location, name of publisher, year published
Number of Pages
You can either begin your report with some sort of citation, or you can incorporate some of these items into the report itself.

Next, try to answer the following questions to get you started thinking about the book:

Author: Who is the author? Have you read any other works by this author?
Genre: What type of book is this: fiction, nonfiction, biography, etc.? What types of people would like to read this kind of book? Do you typically read these kinds of books? Do you like them?
Title: What does the title do for you? Does it spark your interest? Does it fit well with the text of the book?
Pictures/Book Jacket/Cover/Printing: What does the book jacket or book cover say? Is it accurate? Were you excited to read this book because of it? Are there pictures? What kinds are there? Are they interesting?
As You Read
While reading a work of fiction, keep track of the major characters. You can also do the same with biographies. When reading nonfiction works, however, look for the main ideas and be ready to talk about them.

Characters: Who are the main characters? What happens to them? Did you like them? Were there good and bad characters?
Main Ideas: What is the main idea of the book? What happens? What did you learn that you did not know before?
Quotes: What parts did you like best? Are there parts that you could quote to make your report more enjoyable?
When You Are Ready to Write
Announce the book and author. Then, summarize what you have learned from the book. Explain what happens in the book, and discuss the elements you liked, did not like, would have changed, or if you would recommend this book to others and why. Consider the following items as well:

Principles/characters: What elements did you like best? Which characters did you like best and why? How does the author unfold the story or the main idea of the book?
Organize: Make sure that most of your paper summarizes the work. Then you may analyze the characters or themes of the work.
Your Evaluation: Choose one or a few points to discuss about the book. What worked well for you? How does this work compare with others by the same author or other books in the same genre? What major themes, motifs, or terms does the book introduce, and how effective are they? Did the book appeal to you on an emotional or logical way?
Recommend: Would you recommend this book to others? Why? What would you tell them before they read it? What would you talk about after you read it?
Revising/Final Copy
Do a quick double check of your paper:

Double-check the spelling of the author name(s), character names, special terms, and publisher.
Check the punctuation and grammar slowly.
Make sure you provide enough summary so that your reader or instructor can tell you read the book.
Consider adding some interesting quotes from the reading.