You do not have to be brilliant or a genius. But there is always something you can do that is
probably pretty good. Just find out what it is and when you go in there just do it very well.

Always be an optimist at heart.
Because, an optimist successfully identifies things at which they are pretty good at. They
know that if they work hard enough at them, they will become really good and successful.

Learn to face your fears and act.
Be willing to push your comfort limit. When you do, you might fail. When
you fail, start over, armed with the knowledge and experience that you
gained from your failure.
If you want to become self confident you need to do three things.

Become an optimist.
Face your fears and act.
Surround yourself with positive people.