I file my negs chronologically as mentioned above. I have however split the 35mm negs away from the 120/620/127 negs which seemed like a good idea at the time, but was definitely a mistake in retrospect. Have been planning to fix it and amalgamate the sets, but never will. I also have a ring binder for sheets of negs which I have yet to scan. The idea being to have a holding area for recent negs to go into so they won?t get damaged before they get scanned and then eventually filed with the others.
In reality this holding area still has significant number of negs dating back to 2003 and is in danger of spilling over into another binder, so the system has failed. Actually, this is all part of the reason I gave up shooting film for several months from the end of May this year until recently - the situation was becoming unmanageable. It's no better for the break, but at least it's no worse
Digi photos and negs scans are filed (and backed up!) chronologically by year in 12 'month' folders with sub folders along the lines of "France - Sept 2008". I don't tag my photos although I really should.
Chances of me finding a specific neg from years ago for printing etc. run at about 40% based on experiences over the last 24 months.