Z serves are very difficult serves to return. They cut across the court diagonally in front of the returner. This makes it difficult to time the return shot. A properly executed z-serve will land deep into a corner and near a sidewall, and because of the spin on the ball, will come out mostly parallel to the back wall.
Try hitting Z serves at various speeds and heights on the front wall.
After hitting a z serve, immediately move into center court position and watch the ball over your shoulder.
IMHO, lob serves are not defensive, because if done correctly, they put you in an offensive center court position and your opponent deep in a back corner.
Most beginners have trouble controlling lob serves because they put too much energy into the ball by using a big forehand swing. However, the lob requires a new stroke technique. The lob stroke has the fewest moving parts, like putting in golf. To gain control, you need to lock your wrist and pin your arm to your side. They remain locked throughout the lob motion. Use your shoulders to move your arm and racquet.
Plus, you do not need to put much energy into the ball, so use a very short backswing. The lob stroke should feel more like a push. So push the ball to a target point on the front wall.
When hitting a racquetball, it is more efficient to use your biggest muscles. This means rotating your hips, upper torso and shoulders, with your arm going along for a ride.
The racquetball backhand starts by turning your back on the target (front wall) with your arm bent at 90 degrees. Then you simply uncoil your upper body. Your arm remains relaxed and will fly out to an extended position at the point of contact with the ball. You should feel like your motion is accelerating during the entire swing. Completely follow through with your arm until you are completely facing the front wall. A successful backhand stroke is flat and level throughout the hitting zone.
Maintain your athletic position during the entire swing and follow-through. Do not stand up straight at any point during your swing!
Here are a series of videos which go over the basic racquetball forehand technique.
Key points in a mechanically correct swing include:
