After articles about "Giving in", "rage and negative emotions" and "tension" this time I'll have a look on how to handle the tension. There are a lot of situations at the Oche that can stress you, that might give you a hard time. It's important, that you gear up to them already in your preparation.
Do you know what your strengths are and what your weaknesses? Can you assess your achievements? In a match you only control the result of your practice. Do you sometimes expect too much from you? The more you manage it not to think about how good or how bad you play in a tournament or in league the less you stress yourself and start only to enjoy the match the better you'll play and the more successful you'll be. So the result will be the best you are capable on the day.
Are you a practice world-champion, who shows great performances in practice but in contest stays far behind his best? Then check, what it might be that irritates you. Often those are the unfamiliar conditions, which disturb your rhythm. It's a big difference to play a big tournament or in your home pub, whether ten friends from the team watch you or a hundred cheer up for the local hero. It's best to practice before the tournament in similar conditions, that means at an unfamiliar venue, not at the usual time and with as much spectators as possible. You can learn to gear up for the stress. Then it will not be such a big problem during an important match.
Are you really fit? Did you practice well and did you practice enough? Did you have enough breaks to recover and did you sleep enough? Did you eat reasonable? Your body has to be really fit too.
Are your points in good condition? Have you got new shafts and flights? Do you wear clothes that feel comfortable and in which you can really move? When you stand at the Oche the next time, you should make sure you really have done everything to play great darts at the day. Then you'll be able to stay calm and you will feel confident. Good luck!