Basic things
1.) Professional appearance - Suit for men, equivalent for women - basically don't look trashy or like you are going to the club. Brush your teeth, check your nose for dirt. I'm being very serious this, remember, first impressions are everything.
2.) Shake everyone's hand in the room - if multiple people are being interviewed, shake their hands also
3.) Be familiar and have an opinion on physical therapy: current issues
4.) Know basic questions such as Why PT? Why not another profession?
5.) Why this school? - Know something about the program you are joining, not just because it was the only one that would give you an interview. Throw in something about the faculty
6.) Tell me something about yourself. Really think about this one. Some people can't or don't like to describe themselves and freeze up when asked this question.
7.) When you are done - shake every interviewer's hand and say thank you.
Pre-interview - while in waiting area - chat with those in the waiting room, don't be obnoxious, loud or rude. You never know who will see you or hear what you are doing.
Never be rude to the Physical therapy's department secretary or assistant.