This article lists some important things parents can do to help their children become good writers: http://www.pbs.org/parents/experts/archive/2013/01/a-recipe-for-raising-great-wri.html
It's important for all of us to remember the developmental progression, as the author outlines. One other important consideration is to remember where each child is developmentally, regardless of their age and/or intelligence. If we push too much or expect results too quickly, that will turn what should be an interesting and fun activity into just another chore to be gotten through as fast as possible.
This is another reason toys that build imagination are so critical, stories are full of rich meaning and children understand this at a young age. They are so much more than recitation of facts. Stories help children make inferences as to what is happening beneath the surface, so that they can better understand the subtleties of human interaction and thus build their social-emotional skills.
By breaking down writing into its smaller stages and helping children achieve competence and mastery at each stage, we can give them skills which will enhance their relationships over a lifetime.