J.R.
I have found the most important thing is to let natural consequences happen--love the ice cream/cereal response! If you get on your soap box and punish you are giving them undue negative attention (maybe they are looking for attention?!), so you need to let them get 'caught'. Tell friends and have them in on the 'joke'. They need to be called to the mat subtly, but effectively and not just by Mom & Dad. They aren't stupid and they do think about why things didn't go the way they planned. We all learn by consequence--don't touch that-it's hot--they touch and get burned. The most effective lessons are those that teach. It works for more things than just lying, and sometimes consequences can have penalties (like losing privileges). I had a son who lied (all minor stuff-like the hand washing), and I could lecture and punish til the sun went down in the west, but it wasn't until he paid the price outside the home that he figured it out. I wish I had this advice when he was tiny...I would have been a much better mommy! He now knows better.