When capturing moments it is your choice as to which moment to capture. Not all moments are created equal and to know the difference is a skill that needs to be honed.
Observing the rhythm of the scene, be it a concert, a play, a wedding or pretty much any event is key in finding that split second of tension. Watching the players with intent will help in anticipating what will come. You can look through the view finder and focus on one part of the action but you will risk losing the moments you will not see out of your line of sight. Putting the camera down on occasion to see what the entire scene looks like is a good start, as well as resisting the urge to chimp.
Feel the rhythm my friends..