1. Plan early. Even before University classes begin, explore possible sites. I went to my son's middle school and requested to be placed with his favorite teacher, so I could see why he thought she was so great.
2. Ask the Volunteer Coordinator at the school for recommendations as to which teacher likes to work with volunteers. Not all do. I was fortunate in that one of the better volunteer supervisors just happened to be the same teacher as my son so dearly loved.
3. Approach the initial goal assessment assignment with genuine interest. The clearer you are about your goals, the more likely you will endeavor to satisfy them. If you are able to communicate these even informally to your supervisor, your experience is more likely to be rewarding. (I hope that the formality of this assignment becomes more relaxed over the years. The goals/objectives management style doesn't fit many volunteer situations, which are informal by nature. I've lobbied less bureaucratic paperwork concerning this assignment. If you continue the crusade, it may come to pass!)
4. Keep a cursory journal, e.g. what did you do and with whom on which day. This has been handy for learning names of students, and keeping me on track, and helps if I forget to record my time on the timesheet. A related note: if possible, post your timesheet on the wall in a place that both you and your supervisor can see it. Helps to build trust and accountability.
5. Confer often with your supervisor. Ask in advance if she might have 15 minutes this week, e.g. to talk. Be respectful of your supervisor's experience.