—Prepare, but don’t overprepare. You can get tickets right now on the Festival website (http://www.waterfrontfilm.org/), and if there’s something you really want to see, I’d recommend buying tickets early. But you can get tickets at the Festival as well, either at the main office (249 Mason Street), or at the individual venues. If you have some empty slots in your moviegoing schedule, pick up a program while you’re there and see if anything jumps out at you. Or keep your ear to the ground and listen for what people are talking about.
The WFF is incredibly well-run. While the office gets awfully busy during the festival, if you get to your venue nice and early, you’ll be able to get tickets. Just be smart about getting there on time, and you shouldn’t have any problems.