Nancy's scheme really is a great way to go. It's so easy to find things that way.
I'll stare at yours as well but at a glance there was only one thing that popped out to me.
I'm also going to stick in a Miscellaneous folder in each section to give me a place to dump stuff that don't seem to fit.
I can't remember the whys and wherefores but something/someone convinced me that Misc folders were to be avoided.
The problem with Misc folders is they are on their face just collections of random (unorganized) files.
Somehow I ended up with pretty much the same thing as a 'Misc' folder but I call it 'Archives'.
Note that there is a subtle but important difference between these two labels because they imply the process that is being used.
With an Archive the whole point is to maintain/extend the organization of your files and folders while documenting.
Whereas 'Misc' is an unorganized collection, 'Archives' is intended to be organized, even if only at a later time.
In practice anything that you run into in a folder that doesn't belong there is either 1) moved to where it belongs or 2) Archived
What this means practically is that every folder you create can have an associated Archive. It doesn't have to but your most active folders will probably have one. If the assets you are looking for in a particular area of the production cannot be found they are more than likely in the Archive.
Why bother with this methodology?
It adds the element of Rapidity to (temporarily) organizing your files.
If something isn't needed in a folder drag and drop it out of the way into the Archive.
Later in the production cycle, when you are not in the peak creative mode, you'll put on a different hat and organize that Archive.
If in looking into the Archive you see it already well organized you can simply rename the title of the Archive and move it to where it should reside.
Underneath it all I believe is our understanding of what the words Archives means to us versus the word Miscellaneous.
Archives gets us into a mode of backing up, organizing and preserving files whereas Miscellaneous files are unknown, unrelated or simply set aside.
I should also say that I feel I have moved one step beyond this scheme of Archiving but I haven't quite locked down my approach to that.
It's hush/hush secret proprietary stuff that helps me (in theory!) be more organized and more productive.
An element of it is that any key to rapidity must work on/with/against the principle of 'garbage in. garbage out.'
In this realm we need something to play the opposite role that is played by the Archives folder which is one of collecting, storing and categorizing useful assets; that's the backend of the store. At the front end is Research and Development which is required in the rapid collection and processing of useful information and ideas that need to be assessed, procured, prepare, processed and fed into the project.
So, a whole lot of words here to say I think you need two folders that bookend your project; one for information and assets flowing in (Research and Development) and one for those you aren't currently using (Achives). Note that for our purposes here Archives is also a (temporary) waste folder.
One final addition.
You need some type of journal. While this could double as your Research and Development folder I confess I alter the way I implement this one from time to time (most due to not having a consistent project to work on but I think to keep the process itself fresh and interesting vs unbearably boring). Something that has helped me in the arena of documentation is to create a folder with the current date and then add matters of interest for that day into that folder. The benefit of this is that it helps you sort through the issues of the day quickly and keep moving toward your goal. The downside to this naming scheme is that after that day has passed you cannot determine by the title of the folder alone the contents of the folder. Of course this is where the search function of your computer comes in and it's always a good idea to leverage the power of search tools when the goal is rapid processing of information. The most important thing about these journal entries however is that they are documenting your journey. If later on you have any question about where a particular idea came from or where an asset is located important clues will be found here in the journal. Important processes will be recorded. Important ideas not yet explored. And all of this because you took the time to keep a journal.
Note: If using the date as the journal folder title my recommendation is to use the following format; "20120204 (plus title, description or focus as necessary)". This will allow your operating system to automatically sort them.
So, to recap:
Journal folder (Titled by Date)
Purpose: Document your Journey
R&D folder (Titled by Subject)
Purpose: Organize assets for use in your project
Production folders (Titled by Production Number)
Purpose: Keep the Production simple and organized
Archives: (Titled by Subject) Usually only added to a folder as a previous file in that folder is superseded
Purpose: Temporarily store assets that are not being used
Backup: (Copies of Originals - More preferrably the originals!)
Purpose: Maintain the original files or authenticated (tested) copies in a safe and secure location
The above is a general system of file structure I try to use mostly because otherwise I am a very disorganized person.
More accurately, even with the above I am still a disorganized person.