In general I'd say it's important to be able to open one's eyes to the truth and to speak the truth. By doing so you not only set an example and autmatically teach a good way of living to the people around you, you also create harmony. Teaching is quite the complex topic, and it should be adjusted depending on the situation. Kids for example learn a great deal through imitation, they learn as you do, not necessarily as you say. I think teaching is most effective if adjusted to the particular character of the person.