Confidence just helps make everything go more smoothly, often providing the decisive competitive edge. Some describe the relationship between confidence and performance as an inverted U, similar to the relationship between arousal and performance. Maintaining an optimal level of confidence is important because overconfidence, or a false belief in one's ability, can also lead to reduced effort and performance. Frequently image successful performances. Beat up on players slightly below your level occasionally to keep confidence alive.
Some players never learn to win or develop confidence because they are always overmatched.
Make a list of your strengths. Review this list regularly to remind yourself of how great you really are. Eliminate negative thoughts and memories. Have a general strategy going into each competition. Confidence will grow as your plan is executed.