Police sergeant exams consist of a written section and an oral section. While questions may vary among states and localities, common questions consist of topics such as constitutional rights, search warrants and management issues.
The written section of a police sergeant exam often consists of multiple choice questions. A local civil service commission may have a study guide available for either free or for a small fee. Examples of possible common questions are: "What is the process of locating on a map where crimes occur in a specific geographic location?" (Answer: crime mapping) and "As a supervisor, you should know that the evaluation of your subordinates' performance is best evaluated..." (Answer: continuously).
The oral section of the exam is conducted by a live panel. Questions are specific to the procedures and policies of the locality in which one is either seeking employment or advancement. Be familiar with all the department's regulations, as one does not know in advance what questions will be presented.
There are a number of study guides and books available to help prepare for a police sergeant exam. A few of these books are Barron's "Police Sergeant Exam," Arco "Police Sergeant, Lieutenant, Captain Promotion Exams" and the Cliffs Test Prep "Police Sergeant Examination Preparation Guide."