There are ways to deal with stage fright.There is a lot of literature out there on the subject, but I would like to emphasize just a few points that I think can help the most.
BE PREPARED! Practice, practice, practice, and then, practice some more. If you are really prepared, even if you get anxious when you are on stage, your technique and your familiarity with your piece will take over. Once you realize that you have a solid base to depend on, after a few seconds your anxiety should diminish. Preparation involves knowing your notes, your rhythms, your lyrics, the interpretation, your entrances, your moves, and all of the above should have become consistent over the last few weeks of practicing. This is not something that can be learned overnight. It's a process and it takes time. Therefore, you need to give yourself plenty of time for the preparation process. One of my teachers used to say "You don't know a song unless you've practiced it at least 50 times consistently without any mistakes, and by memory." Another teacher used to tell me that "Once you've sung your high notes 1000 times, then you have nothing to worry about". Preparation requires patience, persistence, and consistency. The sooner you start practicing your piece, the better.
PRACTICE WITH AN AUDIENCE BEFORE THE ACTUAL PERFORMANCE. Invite some friends and family members that you trust and feel comfortable with, and give them a short semi-formal performance. The more you perform in front of an audience, the easier it becomes.
EXERCISE A COUPLE OF HOURS BEFORE YOUR PERFORMANCE. I wouldn't recommend anything too intense, but something that will get you moving and your blood flowing. Working out helps build confidence. When you are done working out, you might feel somewhat like a super hero who can do anything. CONFIDENCE. ENERGY. DETERMINATION. Physical activity enhances all those qualities.
THINK ABOUT YOUR AUDIENCE. They are there to support you and enjoy your performance. They want you to succeed. You are a team.
ONCE YOU ARE ON STAGE, take some time to focus, breathe, and try to release the negative voices. Try to feel proud for what you have accomplished and get a little impatient, in a good way. "I can't wait to get on that stage and show off my talent!"
FIND WAYS TO CONNECT WITH YOUR AUDIENCE. Look for familiar faces that bring you comfort. Look for your biggest supporters. Smile and, if appropriate, say something to break the ice. If you come across as welcoming, you will "win" them before you even begin to sing or play.
BREATHE, BREATHE, AND THEN BREATHE SOME MORE! We often get so uptight that we forget to breathe, and the tension accumulates in our hands, chest, shoulders, neck, and jaw. Take a moment in between songs to release tension and focus on all the positive aspects of your performance.
THINK POSITIVE. Before and during the performance. Look forward to that impressive high note at the end of your song. Everyone is looking forward to it, and so should you!
SOME PRACTICAL TIPS: If you mouth starts to get dry while you're singing, find a spot in the song where you can discreetly and gently bite the tip of your tongue. That will instantly produce more saliva and it will help with the dryness. Have some water nearby. There is nothing wrong with needing a few sips of water during your performance. Before the performance, take some time to relax alone. Focus on your music, your energy, and the energy you will get from your audience.
Feel proud, excited to share, passionate about your repertoire, and confident in your abilities. And, remember, if you make a mistake, move on and forget about it.
Finally, try to get into what I call "the sweet space" where nothing else exists but you, your music, and your heartbeat. You are the center of your own attention. You enter a space where you feel grounded, and from there you can get lost into your music. It is an intense stage of focus that many performers claim creates an intense feeling of euphoria. And by the time they are performing their last song, they feel sad that their performance is over. They want to do more because the "sweet space" I described above is just that: sweet. And, just like any sweets we enjoy, it becomes a craving and it gives you the energy and urge to perform again and again and again.
Stage fright lives inside our minds. We can control our thoughts, and we have the ability to turn negative feelings into positive energy and actually enjoy fully the moments leading up to our performance, and even more so the time we spend on stage. It is YOUR time. Enjoy it!