Playing at net in doubles is usually the only time a tennis player might qualify for hazard pay. If your opponent is close enough to the net as well, and hits the ball hard enough at you, you might be in for an unpleasant experience if you don't know how to defend your body.

Many beginners are unaware that there is a proper way to protect your body in this situation. When playing at net, your racquet should be held up, at chest level, with your "off hand" held loosely near the throat of the racquet. The racquet head should point to the left of "straight ahead," roughly across your body; this will allow you to quickly move the racquet face only a slight distance to the front of your body or face for a backhand volley if the ball comes at you.

With the racquet held in a backhand volleying position, racquet face in front of your body, you can protect just about every part of your body from head to net level.  Conversely, it's almost impossible to protect your body with a racquet held in the forehand volley position.

That doesn't stop some players from trying.  Many times, players find themselves trying to think about what side they want to use to defend themselves, while the ball is arrowing towards them.  That is not the time to be thinking about what to do.  While at the net, you must always be ready to instinctively pull your hand sideways, get the racquet face in front of you in a backhand volley posture, and deflect the ball.  If you have to stop and think, it's too late.

So, to sum up, there are two keys to defending yourself at the net. First, make sure to be in the ready position with your racquet ready for a quick backhand volley. Second, work on developing the reflex of bringing the racquet face up into a backhand volley posture, rather than doing the normal human instinct of reaching up with your hands (which brings the racquet into a forehand position). Moving the racquet to a backhand volley must become instinctive when the ball comes at you.

Work on developing that instinctive backhand volley, and you'll stop everything that comes your way.