The worst way to start a talk is to waste five or so seconds trying to work out how to load the Powerpoint presentation, i.e. how to start the slideshow in fullscreen mode. “Where’s the mouse? Where’s the little icon to click? It’s not where it is on my computer. Can someone help?”
The answer is: press the F5 key, and the Powerpoint presentation loads automatically. (If you’re on a PC. If you’re on a Mac, either press Control + Shift + S, or buy a PC. Or, sell your Mac, buy two PCs, and learn how overpriced Macs are at the same time.)
So, press F5. For God’s sake, press F5!