There is no certain way to score, but the best shots you can take at the goalie are: 1) low on his glove side, about six inches off the ice, and 2) high to his stick side, just under the crossbar of the goalpost. I do not have anything against slap shots, provided the players do not lift the stick too high. The higher you take back the stick, the more time it takes to shoot and the more time it gives a defenseman and a goaltender to get ready. And with a short backswing on a slap shot you get much better accuracy and a much better chance to catch the goal-tender before he has had time to get set.
The keenest eyes and the best concentrators in the house will not always know exactly who scores a goal because many shots that start a good distance away are tipped in amid a tangle at the goal mouth. Don't worry. I've learned in a long life in hockey that all goals are good ones, especially your own team's.