Getting an interview is reason enough to congratulate yourself! The selectors have looked at your CV or application form and are impressed with you and want to know more about you. You probably fulfill most of the personal specifications.
Now you need to build on what impressed them about your application. It’s important to work on your interview skills. You might have the right skills and personality for the job but it is important to prepare beforehand so that you demonstrate these at the interview. Work on your presentation skills so you come across as confident, friendly and the kind of person an organisation would want to employ.