The only way to avoid negative feelings during interviews is to maintain positive ones. Before you interview, get to know both yourself and your PE. Find out everything you can about the job, the company, and the people you will meet. Think about how you would act in the job. Imagine yourself in the environment of that company Picture yourself as an employee there. The more you know about the company and the more you can imagine yourself working there, the less nervous you will be and the more positive an image you will project.
During your first few interviews you may still feel some nervousness. Don't worry about it. It will lessen with time. During the next few interviews you will find yourself improving your interviewing skill. You will get better and better. In fact, many job hunters end up enjoying interviewing so much that they miss it once they have accepted a position. They enjoy interviewing because it gives them a chance to show off "people skills" they have developed and perfected. It also gives them an opportunity to meet new people in their profession and to learn about their industry and specialty. Above all, many job-hunters enjoy the challenge of interviewing, of trying to get a PE to make them a job offer. You may not believe it now, but you too may enjoy interviewing. In fact, you may like it too much. So a word of caution: Never become so overconfident or cocky in your interviews that you lose sight of your main purpose to get a great job.