Maven,

Here's an intersting site: http://rosemond.com/index.php.
I don't know if you are familiar with John Rosemond. He is a family psychologist who has great ideas about disciplining children that are about effectiveness, age-appropriateness, and that encourage the true meaning of 'discipline' (to make a disciple of.. to lead toward).

Anyway, I have always admired him and his suggested methods (except one I strongly disagreed with). He has an article on this site about his views on spanking and it mentions appropriate ages and effectiveness.

He used to write a twice-weekly column for the newspaper in the town I came from. I enjoyed reading his column that detailed a particulary problem and offered a solution, using affirmative dicipline, done with matter-of-fact firmness and calmness to show that there are consequences for one's actions. He talks about how to set appropriate consequences and what to do when that consequence doesn't work. He has a lot of good ideas.

I hope this is useful to you as you explore the idea of disciplining.

(edited to add trigger icon)