In addition to the good suggestions here: - vigorous exercise the day of, prior to the talk - deep, yoga style breathing in the minutes before Your body can

In addition to the good suggestions here: - vigorous exercise the day of, prior to the talk - deep, yoga style breathing in the minutes before Your body can only sustain the adrenaline response for so long, so if you have an afternoon talk allow yourself to think about stepping up in front of the crowd to keep it going, so to speak, such that by the afternoon, you're pretty calm. There's also a mindset. I try to think of some of the most inspiring performances I've seen (surfing in my case) where they didn't just survive but dominated it. The goal is not to just survive the talk but to kick ass (meaning of course, getting your message across). Confidence comes from doing. Also, record yourself so you can get feedback and improve. Good luck!