Those with quiet voices need to practice speaking across the room to someone who will signal you if you are too quiet. A good speaking stance is relaxed but upright, hands to the sides, feet flat on the floor, chin up and proud. Don't freeze or become rigid. Don't pace or move without purpose. Wear nice, comfortable clothes.
Nothing is worse than fiddling with uncomfortable garments while everyone watches.
Leave your long hair alone. From the time your name is called until you sit down, act like this is the most exciting thing you could ever want to be doing with your time. Your interest in your own story will allow your audience to be interested as well. If you sound bored out of defensiveness, your audience will definitely be bored as well. Practice and then practice some more.