A fast unit turn. A fast uncoil. Fast upper body. Fast lower body. Defend the contact point according to the arc made in front by your own arm length. Use the flex bar. Twist into a U, and twist shoulder to shoulder with the intention of increasing speed on unit turns. Use fast energy to increase frame speed on all shots. Intend to learn to increase speed on coiling/uncoiling and you will. Intend to increase frame speed on serving and you will. Intend to increase speed on returning serves and you will. There are energy flows inside the body the correspond to your blood vessels and nerve pathways, but are not measurable yet with meters, but they are there anyway. Become aware of the relationship between relaxation and speed, yet intended speed. Learn to become a lull master. A jamming master. A finishing master. Learn to recognize the relationship between lower body coils and upper body coils: upper is sideways twisting, lower is choppy/fast small steps and quick leg/footwork. Keep both moving fast no matter what the incoming speed of the ball, slow/fast/medium. You only have one speed to master: fast and smooth and relaxed. That's why federer is the best of all time. Speed is king in most games, and tennis is no exception. The only way to become faster is to become more relaxed/faster. Allow high shots to be struck way out front, and low shots to be struck very close to you. Use the same speed on first/second serves. Use the same motion, but vary toss location. Attack all shots with relaxed speed and relaxed confidence. Become a faster player with your will/intention/technique. Volley contact point is the same even though continental is used versus ground stroke grip. Don't go high/low on low volleys, as you will go long. Line up volley hand height with incoming height: high ball/high hand/low ball/low hand. High ball out front and chop down. Low ball, low hand and keep frame still and use feet/body to drive low and away. Serving energy/speed has to be very high. Coils very extreme to hit great serves. Second serves must be struck with fearless energy and speed. Keep frame on path way so that you feel it is right, and use shoulder to rotate frame faster, and snap forearm, not wrist into serves. ARch back for higher elbow and more kinetic pathway for serving big shots. It's like a sneeze, coil and uncoil at 100mph sneeze speed. Did you ever notice how many low balls you netted? Went out too far forward and didn't let the ball into your body enough. Ever notice how many high shots you went long on? Waited too long and tried to hit at the same spot you use for medium shots, and went long. This is the same error: tried to use the same contact point regardless of ball height that you use on a neutral height shot, and missed due to being on top of or underneath of the ball. Listen and use these and you will go to a new plateau tactically. You will stop making so many ues. Ever notice how many coaches are trying to get their students to arrive at a higher frame speed? More rpm, more pace, more penetration. Those who learn to do this under pressure are the better players. It's not hard to see why. They use high frame speeds to hit better shots and do it under great match pressure as a natural flow of their own energy. No thought involved, so they stay in the zone unconsciously.