In a tennis match each player has waves of good and bad play. You may run off a string of good games and then have a string of error filled games. The trick is to get through the bad wave quicker and be ready to ride the good wave. Here is some help in how to do that:
recognize the wave (in your game and your opponent's) and realize it won't last forever
stay positive and up-beat during the bad wave, keep your head up and your feet moving
stay loose and keep going for shots during your good and bad wave
above all else, have fun out there and enjoy the process not just the outcome
That last one can make your good wave last the rest of your life.