Try to keep your remarks to under two minutes. Organize a shooting drill that keeps balls and players moving. The rest of the players form two lines on either side of the goal posts just off the playing field. A' goes to the back of near line after the shot. Limit the shooting distance and number of touches before the shot according to age and skill.
Parents can help collect missed shots or kids have to chase their own high and wide ones.
Keep the lines moving. Captains are called out for the coin toss by the referee. When they return, bring the team together for a very brief pep talk. A big cheer, and starters take their positions on the field. There should be a minute or two to warm up the keeper in the goal area you will be defending and to pass a few balls among the players who are in their positions.