Preparation is the blue-collar part of a stroke, where the real grunt work gets done.  Depending on your final position to the ball and your tactical choice, the forward stroke may be slow and smooth, but getting your feet set and your racquet back has to be done in a hurry--like yesterday.  Your opponents, dastardly folks that they are, can deprive you of good position, but the only one that can make you late is you.  The quicker your preparation, the more composed you'll be as a player, and the more options for placement you'll see.

Preparation starts with your feet.  Just before your opponent is about to make contact, and regardless of where you are on the court at the time, you should make a little hop in the air that finds you landing on your toes.  The split-step is done at this moment because the instant before your opponent's contact is when the ball is furthest away from you, and you have the most amount of time for what comes next:  the shoulder turn and back swing.

Wherever you are on the court, you'll know to which side the ball is coming when it crosses your opponent's service line, moving toward you.  That's all the information you need to start your ground stroke.  Turn your shoulders completely and have your back swing completed before the ball hits the court on your side:  beat the bounce with your back swing!  Volleys are nearly the same.  Split-step when your opponent is about to hit.  As soon as you see the ball's direction, make a small shoulder turn and ready the racquet.  Do the work!

c Keith Shein