When interviewing one of my favorite mantras is practice, practice, practice. You can never practice too much.
If you have a friend or family member that you feel comfortable practicing with be sure to ask them if they will help you out. Your Career Development Office at your college would also be happy to have you come in to do a mock interview as well.
Recently I have been conducing a number of mock interviews as students begin to prepare for the job market after college. This week I had an especially interesting mock interview that started out poorly but the student ended up getting the job.