The answer to the question "How do I make sure I'm confident enough in my routine that I don't fall flat on my face" is simple: practice. But the harder questions is: How do you know you've practiced enough? Vinh Giang from 52Kards takes a couple minutes to give his thoughts on the matter, literally moments before performing in front of a few thousand people. He lives by the old theater standby: "One minute of stage-time is equivalent to two hours of rehearsal time."
It sounds like a lot, but being well-rehearsed means that you're not only able to perform your routine like it was second nature, but you're also prepared for when things go wrong - which is often where a lot of the fear lies.
He also talks about making sure you practice the things you say as much as you practice what you're doing with your hands. It's something a lot of people forget when practicing, but it ensures that delivery and performance is as flawless as they can be.
What about you? How do you know you've practiced enough? Let us know in the comments below.