One of the first steps to GTD is to get control of your 'InBoxes'. My most overlooked inbox was my email at work with literally thousands of messages left hanging around in the main inbox area. Today I took the inbox down to zero using these tips... and it WORKED!
No I didn't read every single message and reply to everything that needed action. But I did basically scan each subject line and/or from field and made a quick executive decision to either categorize each one (or groups of them actually) into some sub folders or use my new best friend the DELETE key. The structure I chose for filing included folders called !Archive, !CreateProjects, !Respond and a future reference called !NeedtoRead (not that I plan on really reading each one, I plan on sorting them by date and deleting anything older than 90 days or so) but that gets them all in one area to sort/delete.
It does feel MUCH better knowing there aren't critical emails lurking in the midst of the thousands of other junk messages. I did indeed find serveral "I should have already (done that, replied to that, fixed that, etc) messages that I can now get into my master project list and tag a next action for.
Now I only have my personal email, physical inbox, and home mail to catch up on.. yikes!