A few general anti-stage fright relaxation tips:
Don't lock your legs. Your knees don't have to be bent, but make sure you have some freedom in your legs. Otherwise your whole body goes tense.
Don't stare directly forwards or focus on a particular point. Keep your gaze soft and use fairly peripheral vision. You can take in a lot more and it makes you less tense (see above)
Perform fiddly stressful actions as you exhale. Again it makes yoou more relaxed. If you feel more relaxed, you have more control. The more control you have, the less reason to worry.
Have fun. You are in control. You have power. Relax and enjoy it.
These points (especially re: leg locking and gaze) apply to music and drama as well. Stage fright is a nuisance, but it's basically irrational, as it's the stage fright that's making you screw up, which makes you scared and so on. Break that cycle by approaching performance in a relaxed state, physically and mentally.
The more you perform, and the higher the profile of performance, the better you get at dealing with stage fright afterwards (ok, this works for me, a few performers claim they always have stage fright. This is unusual). I've performed music in public on many occasions, so I know from experience that how large or important or scary my audience is has no bearing on my technical performance. What it should affect in magic is how you engage your audience, and that is something you can only do when you are confident in your technical ability. People say 'practice'. They are right, that does ensure that your technical ability is up to it, but you have to be in a position to trust your technical ability. That takes some mental work, and is much easier when in a relaxed state.