Are you losing matches even when you think you're playing well… Then it may not be what you're doing wrong, but you are not doing. A tennis match requires you to make hundreds of choices in a very short period of time (usually 3-5 sec. per point) every time you hit the ball and every choice you make has consequences. The best choice will maximize opportunities and minimize risks. The key is to play each point shot by shot and make only the best choice on each shot, which sounds easy but we all know that it's not. Making the best choice doesn't guarantee that you will win the point, but it does enable you to play your best tennis.
Losing a point doesn't always mean you did something wrong any more than winning a point means you did everything right. Train for the worst of situations to be able to react in the best possible way when it happens. You must be at your very best when the situation is at its very worst. When everything is going your way, it is easy to be positive and stay on top of your game. When things don't go your way, you are more likely to get angry, discouraged, frustrated, fearful and doubtful as opposed to more patient, confident, encouraged, determined and courageous. When you evaluate yourself on your worst day, then it will be easier to predict what your future holds in tennis.