Michael Grose has written a free e-book on how to communicate with children.  I'm sharing some of his suggestions with you here:

Ever made any of these communication blunders when trying to get some cooperation from your kids? I call them blunders because they tend to have the affect of making kids’ ears close over.

a) Overtalking: “Jeremy, I have told you a million times can you just turn that TV down!”

b) Martyr statements: “I do this because I love you. I ask you to help and you ignore me!”

c) Comparison: “Why don’t you keep your bedroom neat and tidy like your sister?”

d) The Prophecy: “You’re lazy just like your father/mother….. . You will come to no good.”

e) The lecture: “Now listen to me.!….” Better to record your best lectures and burn them on to CD and tell your children the tracks they should listen to at the appropriate time!”