I used to flip the end of the wings of paper aeroplanes upward and breathe on the head of the aeroplane to make it fly farther. According to John Collins -- the maker of the paper aeroplane with the world record for the longest distance -- I was doing it wrong. This video shows how to do it properly.
This is the video that shows how they broke the world record. Former Cal Berkeley quarterback Joe Ayoob is the guy throwing the plane.