I see many players trying to get too close to the net after they serve, thinking that they must at least be inside the service line to hit the opponent's return. The problem with that is they cannot change directions and cover the court adequately, because they are on the move when the ball is hit and are not in a balanced position, which would enable them to spring at whatever shot the opponent has hit. Therefore, their obsession to get in close after the serve leaves them open to a wide angle, lob, and low return. Speed with balance before the ball is hit is terrific; speed for speed's sake may be your downfall.