Returning serve is much like hitting ground strokes. You position the body, stroke the ball and anticipate much the same way in both cases.
Always stand in a ready position: hold the racket in front of you, in most cases using the grip of your weaker side (forehand or backhand), and keep your feet moving, bouncing on the balls of your feet (see photo). Step a few feet behind the base line when facing a strong server. This increases the angle at which your opponent can deliver the ball, but it also gives you that extra second to focus on the ball and move your grip.
When playing a high-hopping, topspin serve, you might try stepping a few feet in front of the base line and hit the ball on the rise (before the ball starts to drop), cutting off the angle of the "kicking" ball.
Even though the server is in control at the start of a point, I never let my opponent dictate how I return serve; I stand in a position I like best. Since I enjoy hitting backhand returns, I "cheat" a few feet over to the forehand side to increase the likelihood of my playing a backhand.
Try to hit the ball as you would hit a ground stroke, with one adjustment: shorten your backswing while maintaining a long follow-through. This backswing gives you extra time to hit a good return.
Anticipating where the ball will go also saves precious time. Club players unknowingly reveal the direction of their serve by the toss. A toss to the right for right-handers and the left for left-handers will produce sidespin that moves away from the returner's body. A toss in the opposite direction creates topspin that will kick the ball into the body.
It's helpful to vary the type of serve return. Don't be afraid to lob, chip the ball short or swing your return wide against a net-rusher. But don't add unnecessary pressure to your shot against a server who stays on the base line. Hit your return high and deep into the court and ready yourself for the next shot.
Next: passing shots