As a tennis professional and coach, I would like to think that my skills can guide a player towards success in a match. However, a player must be able to do things for themselves on the court that will increase their chance to play well.
A player should pick one or two key technique ideas and remind themselves of these, just prior to the start of the point. Watching the ball, using shoulder turn to get ready, or following through on groundstrokes are all good tips.
Strategy reminders should happen just after a point is played, in between games on the changeover, or just prior to, or after, a set is completed. Since strategy tends to be more complicated, it is better to allow a little more time to coach yourself and absorb the idea.
My advice to the player when they are in the heat of a match is to try not to over analyze what is going on. This is the same issue that coaches’ face when trying to help their players perform their best in a point, game, tiebreak, set, or match situation.
As always, keep things simple and coach yourself at the appropriate times for the best chance of success.