[teeja]

The advice given to radio DJ's might be helpful: you're not talking to 100,000 people. You're talking to one or two people. In this case they're all sitting in the same room, but you can still pick out one or two who appear to be listening closely.

If you have a set amount of time to fill, avoid any anxiety about that by preparing more than enough material, and knowing ahead of time what you'll be sacrificing.

Since you know your subject well, focus on communicating your enthusiasm about it. We've all sat through lectures by people who sound bored by what they've chosen to spend years at.