Most normal people get a little nervous before presenting.
take a deep breath
exhale as much air as you can possibly force out of your lungs
sitting down, push against the table in front of you. the goal is to stretch your stomach muscles, not move the table
choose a friendly person that you can talk to during your presentation. Pretend they are the only person in the room.
choose an empty chair to talk to. Pretend the room is empty.