One of the crucial factors in graduate school success is a good supervisor. While some faculties mandate that you come in with an identified supervisor, others let you start your program and identify a supervisor several months into your degree. Picking a supervisor is a very difficult decision and one that shouldn’t be made lightly.
Sometimes there is an obvious person; especially if you have a defined research interests in mind. However, if you don’t really know, or you have a multitude of interests, your options are quite broad. At that point the question is not “what would you like to study” but “who will give you the best environment to study in.”
I’ll highlight what I think is important to talk about with your potential supervisor, or to at least consider, before you make any decisions. However, everyone has different perspectives, and I encourage you to give your opinions in the comments section below. I’ve also discussed this issue on my other blog (Mr Epidemiology) and I encourage you to take a read of that.