How to organize digital documents for administrative work?
The lovely thing about organizing things electronically is that it's much easier to re-organize than physical paper.  The problematic thing is that you can let things accumulate for a lot longer before noticing there's a giant pile forming.

My own personal solution is thus to start each new commitment as its own single folder.  For example, if I'm serving on a committee, that committee gets a folder and everything about it goes in that folder.  Likewise, I have a folder where documents about required trainings go.  

If only a few documents show up, one folder is enough.  For example, for the journal where I'm an assistant editor, I've got only one folder with just a handful of files, since almost everything I need to remember about that responsibility is in its online system.  When more than a dozen or so documents appear, however, I'll create at least one subfolder that can hold a cluster of documents that I don't want to have staring me in the face every time I think about the project.  As things further accumulate, swelling the contents of the top-level folder or the subfolders I've developed, I'll continue developing structure and substructure reactively.

Thus, by deferring organization until there's a quorum of things to organize, I give myself time enough to learn about the organization of information that I need to do.  By beginning organizing when there's a dozen or so items in a location, I deal with organization at an early enough stage that it's not a daunting and time-consuming task.