In racquetball, the server has an enormous advantage over the returner:
Your primary serving goal is to hit a serve which is not returnable by your opponent, which is called a service ace. Generally, this means you want the serve to bounce twice before it gets to the back wall, and, end up in one of the back corners.
In order to win a game to 15 points, you would like to score at least 5 points per game by hitting service winners. Accomplish this by hitting one of four basic racquetball serves: the drive, Z, high-lob, and half-lob serves.
The drive and Z serves are attacking serves and are hit much harder than the lobs. Normally use either a drive or z on the first serve. If you fault on the first serve, then hit a lob serve on the second. Also, it is vital that the serve is not hit too hard so that it rebounds off the back wall.
The drive serve is hit very low and hard so that it just clears the short line. For a one-step drive serve, start with feet together in a squat or athletic position, drop the ball, and then push-off your back leg while swinging crisply at the ball. Move your body in the direction of the ball. Aim for a low target on front wall so that the ball will rebound off the front wall and travel directly towards a corner in the back court.
The Z serve is hit is a very similar manner to the drive. The only difference between them is the target on the front wall for the Z serve is located about four feet from the side wall. The Z serve will race around the court from corner to corner in a Z pattern.
The high-lob and half-lob serves are hit very softly. Stand farther forwards in the service box. With a more upright stance, bounce the ball to waist height and push the ball up to a target at least half-way up on the front wall. The lob serve stroke is made easier and more consistent if you keep your arm and wrist firm while turning from your shoulders.
The high-lob is going to be hit at least 3/4 up on the front wall. Both lobs should land on the floor very near the five foot dotted encroachment line.
Remember, practice a variety of serves. This way, you can be ready to hit the serve which gives your opponent the most trouble.