I am in the same boat as you, though I haven't even had the chance to interview yet. As for things to mention to principals to stand out, I agree with the suggestion that you ask for feedback so you can improve your interview skills. But tie that into how you are always willing to learn more about your subject/technology/teaching methods. Show them that you are a dedicated to learning and improving your abilities for the sake of your students! You could also ask questions regarding recent studies or news articles revolving around education/your subject material. Ask what they think about x study and how it might be beneficial to utilize at the school, etc. Hope that helps! Good luck to you!