The first step is making a great first impression. There are specific characteristics that pop out too people that show you'd make a good officer. Confidence is the main one. I've never met an officer that was insecure or shy, they have to show confidence. When you walk into the interview room, stand up tall. Make sure you have good strong body language. Don't walk to fast and don't be fidgeting with your hands. Make strong eye contact and shake everyone's hands. This is the proper entrance.
A funny thing on how to pass the police interview is that it doesn't really matter what you say, but how you say it. If you passed the exam, than you already know what needs to be said. You just have to do it in a well-spoken voice, make eye contact and keep your head up. Also don't speak too fast. This continues to reinforce the fact that you're confident. This is how you'll end up passing the police interview.
Learn more about the Police Oral Interview