Three little words can make all the difference in the world. If you are thinking of the three little words that we often wait to hear, those wouldn't be the three. These are three words that I am teaching to my kids, words to use as a filter before speaking.
Before they say something to someone, particularly in a state of high emotion, I am teaching them to slow down and ask themselves those three questions. "Is it kind? Is it true? And is it necessary?" If whatever statement they are making doesn't meet the first two criteria, then it definitely doesn't meet the third one. So, for example, as my son is yelling "You're the worst!!" at me in a fit of anger, I ask him to evaluate his choice of words by that standard. Basically, this rule is the practical, shortcut application of Ephesians 4:29, which says "Let nothing unwholesome come out of your mouth, only that which is useful for building up."
My goal in raising my kids is not just to have children who won't embarass me in public, but kids who are able to regulate their behavior based on biblical standards. Changing just the outward actions only leads to kids who know how to behave when someone is watching, or because they don't like the consequences of misbehaving. Consequence driven discipline is useful in the short run to teach a quick lesson, but it never hits the heart level. Maybe Eddie Haskell rings a bell for some of you.
It takes hard work, for a long time, to see the fruits of the kind of parenting I am trying to do. My kids may not always meet the mark, or look like they are getting it, but it takes a long time to grow a fruit tree.