Tip #2 - Be professional, yet also enthusiastic and friendly. Don't, under any circumstances, be condescending to anyone. If you meet with other graduate students, be friendly, and try to mimic their behavior. If you've been invited with them out to dinner at the end of the day and they get a beer or glass of wine, that is the signal that it's alright for you to do the same. Depending on the graduate student and advisor, we often have the ear of the faculty and are asked for our opinion on students or potential faculty. So be nice and professional, but try not to come off as overly serious. Ask other students and faculty about their current research and ask a friendly follow up question.
Tip #3 - Listen. Obviously, you want to impress whomever you meet with at Berkeley, Stanford, Harvard, Yale, Chicago or whatever - but make sure you listen to what they tell you about the program. You'll want as much information as possible if you are asked to chose between more than one program.
Tip #4 - Be ready with a few basic questions. Nearly every interview comes to a conclusion with, "So, do you have any questions for us?" Be ready with a few basic questions for your audience. If you are speaking to a group of other grad students - go for the quality of life questions - "Are graduate students here happy?" or "So where do most grad students find housing? Where do you guys live?". With a group of faculty, you might ask basic questions about the program or "Would it be possible to speak to a couple of current graduate students?" Either way, just be ready for this question.
Tip #5 - Prepare a 3/4 sentence description of what interests you, but be prepared to talk about it on a deeper level. Graduate admissions committees are typically made up of faculty from a number of different subfields. If you are put in a situation where you are meeting with someone in your general field, but in a different subfield, you'll want to provide a basic description of what you're interested in studying while in graduate school - but don't wax on for days about your topic. Instead, save that for the people you will meet with in your specific subfield. Often, academics ask other scholars about their research just to be friendly and make conversation - not because they are really interested in your topic. Be polite, explain what direction you are hoping to go with your topic, but don't over do it when in mixed company.
