You teach them children to be good communicators by modeling it.
You might expect them to do what you say, but the reality is they learn a lot more from what you do, whether you model aggression or model divided attention. For example, you ask them a question while you're reading the newspaper or you're not paying attention. They're going to pick up on that and they might realize that you're not paying attention to them.
You also want to be aware of other things such as tone, and asking clarification questions.
It goes a long way when you recognize that you've done something that was hurtful or wrong, and apologize for it. There's great value in this and you're modeling for your children that you know people aren't perfect. We make decisions and we sometimes make mistakes; there's a big difference there. When we can take ownership and responsibility of our mistakes and say, "you know what, that wasn't my intention" or, "I wish I had done something else." We are appreciating how our actions have impacted that person. Don't explain it away by saying, "Well if you didn't do this, then I wouldn't have had…" That just ruins the whole thing. When you model good communication by saying, "You know what, I did this and I think it impacted you in this way and I'm sorry for that." You can move on to other topics or other situations. You've moved on by acknowledging their experience and that goes a long way.