Our love and service to our children must come before any of our great words, our teaching and training.
Our time, attention, affection—even when we are tired or have other "important" things on our mind—is what builds a relationship and prepares them to listen to what we have to say.
Only then, once the wells of their need are filled with the grace of being loved, will our words to them about God's grace finally make sense.
Read more about this in The Ministry of Motherhood.