Questions in interview may be about your college education, hobbies, interests or your career goals. Some times it may be about the organization that you are going to work. So you have to be prepared for all the questions in order to give the correct answer and must be very presentable in your interview.
Your interview my last about 30 minutes or more and during this time, you have to be perfectly in accordance so that your conversation and interview answers will impress the panel and you also feel confident that you would get the job.
Preparing for your interview in advance for a couple of days will definitely improve your confidence levels and it will also keep you absolutely confident in selecting your answers.