Facilitate an environment that values effort over avoiding failure.
If we experience players that are constantly afraid of making mistakes it’s seldom a sign that the player is mentally weak or they need to go see a psychologist. Oftentimes it’s properly because of the way that we act & the things that we as coaches say on & off the court. It’s a direct consequence of what we show the players that is important in the environment that we facilitate.
So if we do think that e.g. effort is more important than avoiding failure, then we need to set up drills & in general go about the daily practice & what we do at tournaments in a way where the behaviour off excellent effort is rewarded in the both the non-verbal & verbal communication to the players.
At the same time make sure that the players understand the math of tennis, that they understand that you can’t win every single point & mistakes are a natural part of tennis. That they also understand that if you are afraid of making mistakes you are going to have a really hard time improving on or off the court, because mistakes are a natural consequence of trying out something new, which all of us eventually have to do if we want to improve in the long run.