The concept of volleying in Tennis merely is catching the ball as it is in the air before it bounces, the blocking it and tossing it to the opposite side of the court. Volleys involve complex movements, but when explained thoroughly and demonstrated by the right trainer, it can be learnt quickly.
First of all, the player has to be using a continental grip that is the player is holding the racket like a hammer. After that, ensure the player stands on the service line some feet from the net. Then the coach is to stand at the center or fee feet of opposite position to the player in the court. Ensure you go over the basic Movement for a forehand volley.
The basic Movement is that you are in the proper start position, racket head at eye level, knees bent slightly, then toss! The coach is to let the player know that volleys are not to be swung. To prevent turning at salvos, the player should have the hands released, step the opposite foot forward across the body. Note that, the racket should remain in front so the ball can be punched well.