1. Be yourself.
Fill your studio with students who like you and what you have to offer. Trust your intuition.
2. Pay close attention to the relationship between parent and child.
You will become a part of this family system. Does this relationship seem healthy? Is this a family you feel comfortable with? Do you like the parents? Do the parents let their child speak for herself? Do they interrupt or speak on their behalf?
Here are some of the things I like to do at interviews. Obviously, there isn't time for every one at every first meeting. These are all things I've done and found useful.