Many times in a match you will play and win an exciting point, only to double fault or dump a serve return in the net the following point. Try to clear your head completely of the last point, whether you won or lost it. Just think about getting the next point started.
Typically, an average point might consist of a serve, a return and a rally, three hits. Once you get the point to three hits, you will feel more comfortable and competitive. You would be surprised how many points you play that do not go three hits. After a point if you are the server, think about where you want to serve and what type of serve and how hard you are going to hit it. After a point, if you are the receiver, think about getting the serve back in play. Do not think about too much detail or think too far in advance.
Remember, get the point started.
Good luck on the courts!