It is best if you research in detail the offerings of the universities that will participate in the event in advance and then make a list of questions to which you still need specific answers from university representatives. One of the main benefits of meeting them in person is that they can provide you with valuable up-to-date information on topics ranging from programme content, reputation of the university, and admissions criteria, through to extracurricular activities, funding opportunities, and career services. Doing some prior research will help you extract information which is relevant to your individual preferences as well as make a good first impression on the school representatives on site.