So I'd like to share some tips that will make you appear calm while you are working at expanding your comfort zone. First of all, the very best way to deal with nervousness is too practice. Practice your speech so much that you can do it while on autopilot. That way, your lips and body will know what to do even if your mind has checked-out. While speaking, concentrate on breathing slowly and deeply.
Nervous people have a tendency to take short shallows breaths.
Hum a key before you begin to speak and lower your voice just a tiny bit. The resultant noise will sound less like the pitch of a nervous mouse and more like a normal speaking voice. Avoid nervous hand gestures, too. Don't pretend that you are Adam and give yourself a fig leaf. Don't wring your hands like a substitute teacher in the wildest home room.