Make sure your posture is open, stand with your arms open and relaxed by your side. Often people have a tendency to fold their arms or put their hands behind their back. This silently conveys judgment and superiority to your audience which is not a good message from a speaker.
If you get nervous, you can use an Aikido technique I discovered. Lean on the left side of your body and it will engage your right brain, it’s your creative side. You can not be judgmental when you are right brain thinking. Left brain thinking is critical, judgmental and logical. The “what if” scenario is generated from the left brain.
Another Aikido technique when you need a burst of energy is to apply pressure with your fingernail at the tip of your thumb. It sends energy to your brain. One other method is to take three deep belly breaths. Hold the breath in your stomach for a count of three then slowly blow out the air through your mouth.