The notion that you can volley effectively without changing your grip at all between your forehand and backhand volleys is somewhat inaccurate.

Although many professionals volley without rotating the grip between the thumb and forefinger, there is some change at the heel of the hand.

On the forehand volley the racket grip is usually aligned with the life line of your palm, while on the backhand volley the heal of the hand is a bit more mounted on the grip.

This rotation is instinctive and born from practice, with the player adopting, by feel, the most efficient way to hit the ball.

The best backhand volleys are hit across the body, rather than forward, slicing the ball quite a bit. They are a very short motion, and they firm up at the impact with the ball.

While on groundstrokes it is best to get below the ball and hit up, the opposite is true on volleys. You should hit down, as if your racket was going to the bottom of the net, but with a short and chopping hit.

The racket face should be open, according to the height of the incoming shot.

What works best to learn to copy the top pros on the backhand volley is to advance the butt of the racket across the body, from left to right, as if you were elbowing somebody out of the way.