A process is only a good process if all the steps are executed, and the GTD process is no exception. On a regular basis you need to review your Action Item Lista, and make sure that nothing has fallen through the cracks.
I propose the following as a starting point, but you need to tailor it to your personal working style:
At the end of each day review the tasks that were due on the day and ensure that they are either marked as done, postponed, or dealt with in some other way.