Mind-body techniques provide a good solution to this.

First exercise. Breathe out. Take a full breath in for a mental count of 2. Hold for a mental count of 4. Breathe out for a mental count of 6. How do you feel?

It sounds ridiculous that this does anything. But it relaxes you because your brain recognizes the rhythm of a contented sigh - then rushes to put you in that state. Do that the moment that you stand on stage. Do it again any time you need it. You'll be amazed at how much of a difference it makes.

Next exercise. Put, commas, in. The act of standing silent is an act of control that leaves you feeling in control. Trying to slow down results in, "I'mRacing,I'mRacing, SlowDown, I've slowed down, I'mRacingAgain!" But putting in a comma makes it easy to slow down.

This has a second benefit as well. If we're feeling nervous silence is hard on us. So we put in those filler "ahs" and "ums". It is very rare for people to be conscious of how much we do that. Instead we process it subconsciously, as an awareness of anxiety. And our awareness of our own anxiety, creates more anxiety, and off we go!

And so I like to say, "Put in a pause, or you'll say your ahs!" Try it. Those commas really work.

The third thing is this. When we stand in front of an audience, most of us get a shot of adrenaline. We frame it as "social anxiety". But it's really not. It's social adrenaline. If you learn to interpret it as "on a rollercoaster" instead of "there's a tiger", it goes from scary to fun.

This takes a bit of practice. But (with the mind-body skills), less than you'd expect. And it is easy to find a place to practice if you join a local Toastmasters club.