Watching a pro do pre-conference is alway enlightening. At Agile Africa last year I got in early enough to watch Martin Fowler do some pre-conference prep.
Two things that stuck out. He had a slide he put up on the projector that allowed him to see the Bleed, Crop & Corners of the projector.
Secondly, he had someone with him for the pre-conference check who sat up in the stage and helped him guage the audio / volume he would need to speak at.
