Here's a quick example of what I'm talking about when I harp on preparation over and over again.
Yesterday, as I set up my equipment for a presentation, I noticed that my remote wasn't working. I tried plugging the drive into different ports, but that wasn't the problem.
I realized that the batteries must be dead, so I pulled some batteries out of my bag and changed them.
Again, I switched ports, and nothing worked.
About to give up on the remote, I decided to try another set of batteries. Because, yes, I had about six extra batteries in my bag.
Guess what: The next set of batteries worked! The remote came to life and my presentation went on as planned.
I hope you always have a "Plan B" for whatever might go wrong. But do you also have a "Plan C?" Or even a "Plan D?" Think about every aspect of your presentation, not just your words. Think about your activities, your handouts, your equipment, your venue, your props, your business cards, your hydration, your sleep the night before...
Don't leave anything to chance. And by the way, unexpected events might still happen! But the more you prepare, the calmer and more relaxed you'll be and the better you'll be able to handle those unexpected events.