Do you have things about your life that you don't want your children to imitate? If so, you need to change, and do it now. Children are like a sponge, absorbing, taking in, and emulating everything from their surrounding environment. Therefore, the best teacher for our children is our own personal behavior. All people learn by imitation. We learn new jobs by watching others do them, etc. Children especially learn by mimicking parents. Usually they're more affected by what their parents do than by what their parents say. They learn how to behave by seeing how their mothers and fathers behave and following their example. For this reason, you need to be aware of the "lessons" you may unintentionally be teaching your children. Children often learn without a parent's realizing it. Have you ever walked in on your child using language or gestures commonly used by you when disciplining the child? Do you then think to yourself, "where'd they get that from?" Only to realize they got it from you.
Still don't believe in the importance of teaching by example? Think about your own childhood. How were you most influenced to become the person you are now? Was it mostly what you learned in school? Was it mostly your grade-school and high-school and adult friends? Was it mostly movies or television? More than likely the person you have become was influenced mostly by the example set by your parents and other people who were close to you when you were young.
Children need to see their parents living by good moral principles. But remember that they imitate both good and bad characteristics. Most parents want their children to live better than they themselves have lived. This can happen, but it is rare. The general rule is that children are like their parents. If our children are no better than we are, what will they be like? If your children imitate you, will they lie, deceive, smoke, drink, gamble, dress immodestly, neglect the Lord and the church? Or will they be honest, hard working, and diligent in Bible study, prayer, teaching God's word to others, and working in the church?
Teach your child how to live life by being the person you would want them to be. Kindness to others, helping others, loving yourself, no judgments about other people, no gossip, and everything coming from love. As you learn this in your own self and apply it your child won't need you to speak a word.