The descending part of the flight is generally more painful on the ears. Swallowing or yawning can open the Eustachian tubes and allow the pressure to equalize. See:

http://www.education.com/reference/article/Ref_Flying_Your_Childs/

As a side note, newer plains (787 dreamliner especially) are built to have higher air pressure, closer to that at ground level (6000 feet instead of the normal 8000), which results in less of a change over the course of the flight.

-graham