I met up with some friends last night and did an off-the-cuff show and tell. I left feeling I'd failed to get across what's so interesting about Mailana, reminding me that in my natural state I give terrible demos. Since they're a crucial part of selling an idea, I've had to work hard to fix that. I know I share that affliction with almost every engineer I know, so here's some tips that have helped me.
Accept that it's important
In most engineering situations, if I know something interesting and you don't, you're expected to make an effort to learn it. That's completely reversed when you're trying to sell your idea. You may be certain that it's the best thing since sliced bread, but you're the one who has to make the effort to communicate that to investors, customers or journalists. They have massive numbers of people trying to persuade them to take action, so they can only spend a small amount of time and thought on each proposal. That means you have to spend a lot of time and effort crafting your demo.
Stop coding at least a couple of days before, turn on your web cam, start recording and practice what you're going to say. Watch it back every time, and then do it again. My rule of thumb is that I need to do it at least 25 times before I start sounding natural, ironically. This also comes in handy if you want to produce a web video of your presentation, the one I'm still proudest of is my pitch for SearchMash from a few years back. It sounded crazy to me at first to spend so much time on it, f you don't believe me, just read about the days of prep Steve Jobs puts in for his keynotes.
Show, don't tell
Jason Calcanis's demo guide is spot on. People don't want to hear about your life story, just show them your product within the first 30 seconds, preferably doing something awesome. My Achilles heel is going into all of the really interesting technical details of how it works. That's like having a car commercial with the hood popped just showing them the engine. They want to see what it does for them, not how it does it.