Being an effective parent is challenging, to say the least. :-) Leading by example, teaching self-esteem, self-respect & self-less-ness must never be slighted. If God didn't think we were capable of handling the load, I guarantee you'd never have this cross to bear. A heavy load, with great sacrifices, but with even greater rewards...THERE IS NOTHING LIKE IT!
Proverbs 17:25 says that "a foolish man is a grief to his father and bitterness to her that bear him..." When our children stray from righteous living, it hurts parents to our core, yet our children must learn to function independently and sometimes "bump their proverbial heads" along the way, in order to grasp the lesson.
So let them LIVE! Guide them and provide advice along the journey, but never deny them the experiences that will HELP develop their truest character...the character that will define their life not only comes from the foundation that you've built for them, but it also requires the experiences that happen away from home (and their responses to them). Remember, as a parent, you are not only needed in their lives, you ARE necessary.