Do have interviewers wear name tags or have name plates in front of them. Otherwise, candidates might spend a large part of their consciousness trying to remember the names of the interviewers in order to write a good thank-you letter.
Do hand out brochures about your school, a business card, etc. before beginning so that the candidate knows what to take notes on and what to just observe.
Do act like yourself, but possibly toned down. Candidates want to know what their potential colleagues might be like. If you exhibit no personality, they find out nothing.
Do ask for a copy of a CV or other materials if you can't find your own copy. It's boring and uninformative for a candidate to repeat what is on his/her CV, so you may as well ask about other things or ask details that can't be included on a CV.
Do take notes, if you like. The candidate may also want to take notes. Everyone knows that both sides are meeting with multiple parties. How else would one keep them straight?
Do ask questions related to your mission (if you have one). This is a great time to find out if someone cannot or will not get on board with your program. What is expected of faculty at religious institutions varies greatly, so this is particularly important to convey. If you are a religious institution that requires some kind of religious stance from your faculty, have a conversation with the committee before interviewing about how to explain the expectations.
Don't conduct your interviews in a hotel room. Under no circumstances should interviews conducted by one person take place in a hotel room! Even when there are multiple interviewers, a hotel room is not an ideal venue. What works better are conference or sitting areas in hotels, areas in the conference center that are not highly traveled, etc.
Don't talk only about your institution. If you have a lot of factual information to impart, why not write it down on a handout?
Don't ask only about the candidate. He/she also wants to know about your institution. What you choose to tell is revealing in terms of your priorities.
Don't discourage interruptions during your spiel. This is when candidates hear what you might need to know about them. After a 10 minute spiel, it's possible that a candidate may have 10 anecdotes and facts to relate. That is too many to expect someone to keep in his/her mind. If you don't allow interruptions, you've just lost possibly important information.
Don't ask detailed questions about curriculum, unless you warn candidates in advance that you will do so. Thoughtful faculty members do not make spur-of-the moment decisions about curriculum. Why would you want a candidate who does so? It is okay to ask if the candidate has ideas or thoughts, but it is absurd to require detailed answers based on no research or evaluation of the possibilities.
Do ask (possibly at the end) if there are other materials the candidate would like to share.