Even when you're not going to be first to the ball, it can often be a good idea for the goalkeeper to come out of goal and challenge the opposing forwards. Matt Larsen explains why: "One of the things that I like to do is make the opposition do something – don’t give them time to think. If a 50/50 ball is coming in, don’t let them assume they have it all to themselves. Take inventory of the situation, figure out the odds of you getting to the ball prior to others, and make a play for it. Making a play for the ball will sometime alleviate the unenviable situation for a goalie where the opponent has the ball one on one with you. When that situation occurs, you’re done. They should be able to pick a spot in the goal and hit it – done and done. By putting pressure on them early and letting them know they don’t have a clean one on one opportunity, the odds of them not scoring go up."
As Matt points out, a basic principle of defense- not just for goalkeepers- is that you want to put as many obstacles in front of the offense as possible; increase the difficulty for them. Make them pass before taking a shot; push them to the outside to narrow their shooting angle; if they're about to have a chance for an open, close-range shot, charge out at them so they have to deal with you. Put your body in front of them to fill up their shooting lane. The more difficulties you place in their way, the lower their chances of scoring.
Communication
The goalkeeper is in a better position to see the overall action on the field than anyone else on the defense; so it can be a big help to your teammates if you communicate to them what you see and where they need to be positioned. It can be the difference between a defense that operates as a team, and a defense that operates as just an assortment of players fighting individual battles.
How much you talk to your defense will vary according to taste. Some goalkeepers give direction to their fullbacks almost constantly; others find that distracting, and prefer to only communicate when they see a mistake being made; a full forward slipping wide open for a possible pass, for instance. Either way, though, coordination between you and your teammates goes a long way towards successfully defending the goal.
POSITIONAL PLAY: Keeper
photo credit: Kerry Leonard