Next, go to a local pub for reflection and a pint of stella. Do not concern yourself with any other matters other than the lecture at hand, and even then, possibly try and forget about it. A certain calm may prevail. Then, at least hours before the appointed hour, make your way to the venue via reliable transportation. Make sure you have thought ahead about your 'green room' (pub) close to the venue, there you must sit and observe in minute detail the world around you. See it as a window on the world (I particularly favour The Tottenham on Oxford St when I lecture at the AA, it has a genuine front window on our unfortunate world). Now at this point you will be distracted by the T&A (or other preferences) passing you by, but you must let the snow fall in your head with the aid of a few large ones. Soon enough cometh the hour, and always make sure you are ten minutes early to foresee technical difficulties. Always love the technicians and support staff in charge, partly because you do love them anyway because they support you.
See the students troop in, remember you were just like them a long time ago.
Shut the door.
With luck, and the smiling of the gods, then the magic happens.