Most players prefer either their forehand or backhand. Human nature is to try to stay away from the shot that is your opponent's strength. However, sometimes playing the ball to their strength allows you a bigger area to attack their weaker side.
Many players with a very good forehand or backhand tend to stand with more opening to their strength, which makes it difficult to get the ball to their weaker shot. A good strategy is to hit your first shot or two to their strength, followed by a shot to the other side of the court. This tends to get the opponent hitting their weaker shot while they are moving, often making their shot even less effective. It also allows you to hit your ball to the open side of the court and not as close to the lines, while still attacking their weakness.
Try this measured attack rather than immediately targeting their obviously weaker side. You will likely make less errors as well as forcing your opponent to show that they can hit their weaker shot on the run.