Danah, In my profession, I give a lot of presentations or have public speaking appearances. The tip I can give you about this is just be you. Speak as if you are talking to one of your friends. Never-mind the faces or the amount of faces in the room, just tell a story...we can all tell a story. Confidence will come the more you do this. The only one that knows you are nervous is you. Nerves are NORMAL...use them to your advantage by turning them into enthusiasm. If you worry about a squeeky voice, then that's what you'll get. Nobody knows your story better than you. You'll do fine...Good Luck.
"Back in the thirties we were told we must collectivize the nation because the people were so poor. Now we are told we must collectivize the nation because the people are so rich."
William F. Buckley, Jr.