Drills

Drill #1:
This first drill works on your touches with the laces of your cleats. In a goalkick, it is important that you use the laces because the laces are what makes the ball travel further. In this drill the person is sitting on the ground and the trainer tosses the ball too the foot and the player must return it by kicking it with only their laces. It is a good warmup drill to get ready to do a goalkick.
http://www.youtube.com/watch?v=6vuKiN7TK28&feature=related

Drill #2:
This second drill goes into the movement itself. They place a ball down and go through the movement of what you need to do to approach the ball and strike it. First the trainer has the kids approach the ball without kicking it. he makes them do each movement until the ball should be hit to show the proper technique. After the kids have the movement down, he makes them actually kick the ball but not at full power. A goalkick is all about technique not about power.
http://www.youtube.com/watch?v=fFc9HA0XHvY

Drill #3:
This drill you can use when you get the technique down. What you do is you set up some balls about 10-15 yards away from the back of the goal. The objective is to do a goalkick and get the ball over the crossbar. This drill now combines both technique and power because now you need power to get the ball over the crossbar. Great Drill to measure your progress.
http://www.youtube.com/watch?v=tEZUtVdwyO4