The best way to prepare is to think of examples where you have successfully used the skills you've acquired. Take the time to compile a list of responses to both types of questions and to itemize your skills, values, and interests as well as your strengths and weaknesses. Emphasize what you can do to benefit the company rather than just what you are interested in. Also prepare a list of questions you want to ask the interviewer. Remember, you aren't simply trying to get the job - you are also interviewing the employer to assess whether this company and the position are a good fit for you.