As a martial artist that performed at many tournaments and demos I can tell you that confidence in your performance directly affects your outcome. This is especially true when you're performing on your own. You can mess up terribly and if you do it with confidence many people won't even know.
I was at a tournament one time as a blue belt in front of 5 judges and there was a tie for 1st and 2nd place. I was always told that if you are breaking a tie it's better to do a different form than the one you just performed. I decided to do the green belt kata. I had learned it early from watching other people and practicing it. However I found myself facing the wrong way halfway through the kata. I added an extra kick to get myself facing back the right direction at the end of the kata and finished it as strong as I could. I ended up with first place. After, the only judge that was from our school came up to me and congratulated me on being able to correct it in the middle of the kata, He actually gave me more points because he knew my mistake and was impressed that I never showed it and I fixed it before the end. That day I understood the concept of screwing up with confidence.
I think the best way to develop confidence is time and training. The first kata I performed that day I did extremely well. Which was one reason I decided to do a different kata. I don't think I could've performed the same kata any better. The reason I performed so well was the countless times I had practiced it. When I would get ready for tournaments I would perform a kata literally hundreds of time to make sure I had it as perfect as I could. I strove for it to be as flawless as possible. I do remember times I performed at tournaments with less practice than I would've liked and I remember not being as confident.
Time and training develops confidence. Experience develops confidence. If there is an area you know you need to feel more confident in, practice it. Find some people that you can role play the situation with so you can put yourself in the situation, in a controlled environment, before the live scenario plays out.
