well....there is no real simple answer for this problem. It mostly comes down to the parent.
For the TV thing....thats easily solved these days since you can block anything you dont want them seeing. For most TV's anyway.
But other things...I think that you shouldnt entirely shelter them nor should you let them run wild. Monitor and make sure nothing too bad happens. If its something that they can potentially learn from their mistakes themselves without any real danger to them, then i think it would be a better idea. People (especially children) often learn things much better when its self taught through experience.