It starts with a positive loving relationship with your children, that also include proper discipline when necessary with fairness.
Communication is also key. It is important to teach children how to think in order for them to make proper decisions when you are not around. One technique, which works in a general situation, without any danger or immediate action needed is by asking a series of questions that lead them to a proper conclusion instead of just telling them or demanding something.
Children will feel more respected and when they get it, a light bulb will seem to go off. Just be careful, that a smart kid will then try to use the technique on you.