First, identify the kind of book you're reporting on. If the book is fiction, you will probably have to read it more thoroughly than a nonfiction book, to search for "symbolism" and deeper meaning.
Think about the class and professor. What kind of details does he or she prefer to focus on? Have there been book reports in this class before, and if so, do you know anything about the successful ones? These details can help you decide what to emphasize in your book report.
Look around for additional resources that can help you understand the book more clearly and finish it more quickly. Are there audiobook versions available for your iPod? Are there college-level discussion groups available online? Do you know anyone who has read the book? Was it used in previous versions of the same class?
Skim the book, paying attention to important cues. Pay special attention to the beginning and ending of each chapter. In a fiction book, focus on dialogue to get a general idea of what's going on. In a nonfiction book, focus on concluding points, diagrams, emphasis boxes, and so on.
Take notes as you skim, writing down the page number where important concepts occur -- most college reports require citation, so this will save you lots of time later.
After a day, read the book more thoroughly to fill in details and solidify your understanding. Look over your book report to ensure that it explains the main points of the book and includes a conclusion describing what they all mean together.
Print out your work and do a final proofread, checking for errors and typos. If you will be required to "present" on your book, read your final report twice a day until the day of the presentation to get familiar with it.
Turn in your college book report and enjoy your A!