Head straight down the middle of the field, and when you take a
shot,  curve the ball to one side of the net, and the keeper will find
it harder to save.

Another way of scoring an easier goal, is to head towards the goal
at a 45 degree angle and aim your shot for the far post.

When defending, don't tackle from behind, use speed to come up
from the side and cut in front of him to take the ball.