Confidence and its role.

Confidence is said to play a critical role in a person's mental outlook and ultimate success. In fact we've heard that the most consistent factor that distinguishes highly successful from less successful athletes is confidence. ...

We have long recognized a relationship between confidence and performance. Sometimes it appears that only the greatest people have access to that magical confidence, while all others can only wish for it. ... Everyone can increase their level of confidence and perform better.

Although confidence is difficult to define, it is usually described as thoughts, feelings and actions reflecting self-belief and expectations of success. ... They rarely give their opponent a confidence boost by appearing discouraged or threatened.

It is often asked what comes first, confidence or success? Although it is true that success breeds confidence, it is equally so that confidence increases ones probability for success. ... Confidence also adds security during slumps and helps us sustain effort. ...
Them who lack confidence worry needlessly about mistakes, lose concentration, allow dangerous levels of arousal to intrude, and increase failure by giving up. ...

Although all desires confidence, there is no replacement for competence. ... Confidence just helps make everything go more smoothly, often providing the decisive competitive edge.
Maintaining an optimal level of confidence is important because overconfidence, or a false belief in ones ability, can also lead to reduced effort and performance.
My tips for you to develop and maintain confidence could be:

Increase level of physical and mental fitness, as this will enhance technique and self-image at the same time.
Beat up on others slightly below your level occasionally to keep confidence alive. Some people never learn to win or develop confidence because they are always over matched. ... Confidence is not a luxury reserved for the best. ...