There are many other things I have learned over the years, involved in planning and arranging cons myself. Here are my thoughts on how to make the panel part of the convention program work well. I should say that my experience is from small(ish) conventions, but I think most of this will apply also for conventions with several hundred members.
Topics. Brainstorm, look at other conventions for inspiration, use the special interests of the guests. Test the topics by discussing them yourself. If you cannot keep it going for more than a few minutes, it might not work for a panel. If it's something you know nothing about this might be difficult -- then try instead to come up with interesting questions. If you can write down ten or so, then it might be a good topic for a panel.
Participants. Don't just wait for people to sign up, also actively ask people you know with some knowledge of the topic in question. Try to put together a panel of people who are not only interested in the topic, but will also work well as a panel. Usually you might not know everyone on the panel, but try as best you can to balance the participants. A very loud and talkative person needs to be balanced by a strong moderator, especially if there are some more quiet or shy people on the same panel.
Information to moderators. Don't assume that everyone knows what they are supposed to do. Make sure that the moderators know what their task is: keep the panel on topic, and let everyone get to speak. Provide them with the panel description in the green room just before the panel, in case they forgot their notes. Add some help questions to that, it can never hurt. You owe it to the members to make sure that the panel is really about what it says in the programme that it's going to be about. Interesting sidetracks can be noted and pursued later in the bar (or whatever meeting place your con has).
Information for all participants. Send out an email about a week before the con, containing at least the following information. Don't assume that everyone knows it all! Even experienced panelists might need some reminders.
- A list with the panels this person is signed up for, as a reminder.
- Instructions to check on arrival to make sure that when and where your panels are. Check also during the con, for changes.
- Instructions to meet with the others on the panel in the Green Room just before the panel starts. It will give them time to say hello and make sure that they all agree on what it is they are going to discuss.
- A description of the compensation panelists are offered, whether it is free things from the bar or discount on the membership. Just so that everyone is aware of this in advance.
Leave some space for the panelists to breathe. If possible, don't put the same person on two panels after eachother. In any case, make sure that there is 10 minutes between panels, to let panelists and audience find the next thing they are going to.
Include all information in the printed programme. Yes, the members need to understand what the panels are about. Don't give just a fun title, make sure to provide at least one sentence of description. A nice thing is to also include a very short presentation of the panelists in the programme book, especially if the convention is so large that not everyone will meet everyone. (At Swedish conventions this might be interesting mostly for new fans, since everyone else usually knows everyone already, but nevertheless.)
That was all, at least all I can think of right now. Any thoughts or comments? Anything I should add or remove?
Addendum: someone just reminded me that it can be a good idea to prepare a little guide for each panelist (or other programme participants), just a printed list of items with time and location for each. It's good if it's small enough to fit in the badge holder, so you can easily have it ready at all times. Very helpful!