Why talk to the net player and use signals?
Once the net player knows where the serve will be directed, they can be pro-active at the net.
Tennis elbow is caused by the vibration from your racquet going up into your arm. When players hit the ball outside of the sweetspot, the racquet will vibrate more than usual.
The best tennis players are very focused on serving and returning serve. If a player can develop a good serve and/or a good return of serve, they can control more of the points and take advantage of the opponent’s weaker shots.