Visualizing is a method to use your power of imagination to realize what you really want in your life. It's nothing new or unusual. You use your imagination and produce your wish as a real picture in your minds eye. In reports over successful people we often can read they had inside them a picture of what they wanted to achieve. They were almost obsessed by this idea, they wanted to be perfect and be highly rewarded for this.
First step: Set yourself a goal!
Imagine as exactly as possible what you want to realize. Look for a goal first you really can believe in and were you see the possibility to realize it soon (for example not get afraid when under pressure, but play on aggressively and with courage). It will help you feeling more successes while learning the technique. When you get more used to it, you can choose more demanding goals.
Second step: Imagine your goal as detailed as possible!
Imagine your goal as detailed as possible in your minds eye. Paint this inner feeling of success. Just think your wish is already reality. Imagine in all details what you then feel, where you are, what is happening. Perhaps you even can imagine who'll be there, what you hear and smell and how the people react (for example winning a tournament, a presentation ceremony, an applauding audience, drinking some sparkling wine from a cup).
Third Step: Positive Energy through affirmations!
Be optimistic when concentrating on your goal. Confirm your wish with short, positive phrases, like it would be already reality. Try to disregard doubts or second thoughts and accept the feeling that it's possible to reach your goal. Use affirmations like "I play better every day, I am totally focussed and successful". After some time the phrase will inspire your subconscious.
Fourth Step: Concentrate on your goal, practice consequently every day!
By practising visualizing regularly your wish will become part of your life and gets more and more concrete. The more you see the success in your minds eye the more probable it will be realized. While practicing you should stay undisturbed in a quiet place. The more relaxed you are the more effective it will be. I recommend to practice in the morning after you did wake up and in the evening before you fall asleep to practice for around 10 minutes. Close your eyes breathe deep a few times and start practicing when feeling calm and relaxed. Imagine the realisation of your dream (like described in step two) and speak three times your affirmation phrase aloud.