Review books on subjects you know best so readers will trust your critiques and know what to expect. Reference your expertise frequently in the column. For example, if you're an executive chef who's owned restaurants, readers will value your reviews of cookbooks more than if you had no culinary experience.Your review of a new book on baking might say: "How the author was able to produce a flaky pie crust after kneading the dough is a mystery to a chef like me who takes pains to handle pie dough as little as possible."
Establish an attitude toward the subjects and let your readers know it. While readers expect you to be fair in judging a book's worth, they know that personal likes and dislikes invariably affect your judgments. According to former New York Times editor Monica McCabe Cardoza, your personality helps you to engage your readers. They should know you're a registered Democrat if you've spent an entire column trashing two policy books written by Republicans. (See Chapter 7 of Cardoza's book "Engaging Your Audience.")
Set context by alluding to a book's theme in the first paragraph of your column. For example, see the review "Under the Dome" written by Wesley Stace in the New York Times Sunday Book Review. Stace's column introduces the book's subject---punk---by highlighting the irony that a movement grounded in themes of destruction inspired creativity. That is exactly the theme of the book Stace was reviewing.
Remark on the author's choice of topic but give sound reasons. For example, you might criticize an author for writing a general book on dieting. Your reasons could be that the market is saturated and that a better topic would have been dieting while on a vacation.
Criticize the book's intended audience. For example, an author who explains the principles of trial preparation would be wasting time if his audience is tax attorneys who don't try cases in court.
Comment on the author's writing style, even if he or she does not pretend to be a professional writer. Many readers are put off by a poorly written book no matter how much of an expert the author is.