For a very long time I was a person who interviewed people. Things that stand out are the folks who were apparently helpless and didn't know which airport to arrive at and how to get to my location.
Study up on that stuff for each city you will be visiting. Please!
We have always had folks who insisted on flying SouthWest in Dallas Love Field when our closest airport is DFW International. And I didn't go fetch people from either!
Have enough actual cash to pay for that transportation and don't rely on always using a credit card.
Arrive early to your appointment and take the time to use GOOGLE or BING maps to study your route and the actual appearance of your destination building and available parking.
Go into a rest room and freshen up prior to your interviiew especially in hot climates. Don't look like you've just run a race.
Don't bring gifts to your interviews!
Make eye contact with your interviewers. Very important! Even if you are terrified don't occupy yourself with looking at the wall or the floor.
If you are invited to lunch, do so! A social situation often helps to pick the winners.
I love to ask people what their most successful moment in life has been to this point. If a person says 'when my baby was born' that works for me, but it is also good to hear if a person won a race, even a Soap Box Derby or has done volunteer work.
Don't be sorry if your clothes aren't expensive. My first real interview I was wearing a borrowed dress.
Best of luck to you! I'm confident you will find a school that suits you fine.