Keep your eye on the ball

To watch the ball so intently that, in theory, you actually see the strings make contact with it. Well... maybe... but there are countless high-speed action photographs of great stars that would disprove that theory. However, as a concept, the idea is good. You should certainly concentrate intently upon the flight of the ball as it approaches you, and see it hit. Whether or not you actually see contact, or look away a moment before (as one would usually do in catching a ball) is moot. If you are at net, the chances are more realistic that you do see the actual contact.