A younger friend of mine asked several of us at small group Sunday night what the secret to good parenting and good relationships with our older kids is. (Obviously she understood that a personal walk with Christ is the very most important aspect of success!)
My response - consistency.
I really cannot think of another thing that is more important in parenting. This is true in every area. Parents must demonstrate consistency in their own marriages, consistency in our pursuit of spiritual maturity, discipline of our kids, a big one is encouragement of our kids, we need to be very present in their lives - attend things that are important to them, then there is honesty with our kids... I could go on and on.
Even the Christian kids I know who have lost respect for their parents seem to resent them because they see they don't practice what they preach. We cannot expect our kids to act any differently then we act. Certainly there are exceptions, and it doesn't always mean that the parents did wrong things. Some kids just seem to struggle with authority their whole lives. All we can do is our best to demonstrate a responsible, consistent, Godly life for them!
Generally speaking, what I see is if there is consistency between what we say and what we do, the relationship with our kids can flourish! I pray for my kids and praise God for our relationship every day!