In my experience, I've found that playing music the first day of class is really helpful for setting the mood for my courses. I usually select something upbeat or interesting. For example, I had a dance mix of Latin and African sounds that was really fun. A lot of students were intrigued to find this playing in the classroom and it opened the door to many conversations. Building rapport on day one is critical, so choosing a great ice-breaker is helpful as well. I really enjoy doing two truths and a lie...although with some of my students I've noticed they share inappropriate things (i.e. I've been in prison for 20 years) so depending on your audience it may not be wise. What are some other ways you build rapport on the first day?