Luongo should read-up the hockey
basics on wikihow:
How to Play Goalie in Hockey
Watch the puck at all times, not the players (beginners). For more advanced goaltenders,
watching the play is essential, this is how you can predict what could happen next. For example, if a player is coming down the left wing on you, and there is a player at the right corner of your crease, you should play a bit further back in your net in case the player decides to pass the puck. By just watching the puck, you lose a lot of what is going on. As you develop you should always be looking around you to see what a players options are. Your job is not to guess what will happen, but to know how many options the player with the puck has, and as you develop you will have a sense for what options the player will most likely take. That being said,
you should never lose sight of the puck, and you should always be prepared for a shot.