How can I manage being stressed and nervous on an interview?

You need to go in with a great attitude. If you're thinking about it now, you're going to be ready. Wear something you're comfortable in, and smile! No matter how you feel you need to learn to relax. I recommend making a plan and saying, if this goes well I will take myself out to dinner, or whatever makes you really happy. Reward yourself for a job well done. Don't fidget in your chair, give a firm handshake and look like you're enjoying yourself. If it's the most important interview of your life make it look like that! People enjoy enthusiasm. Speak slowly and clearly and think about your answers before you talk. Make sure you listen. Only focus on what they're asking and nothing else so that your answers are exactly what they asked you. Push all your tension to one part of your body and keep it there so the interviewer can't see it. That way you can still be nervous and keep the rest of your body calm. Tell yourself you'll do well, the mind works in mysterious ways...If you think you're going to do well you will! I promise I have given so many interviews in my life and this really works. Believe me. Good luck, I know you'll do great!!