I've addressed something similar in this thread: File Naming and Archiving.

I work at a marketing & design firm, and all our projects have job numbers. Let's say job number 4287 is the Jones Corp Brochure. So on our file server where we keep all our projects, we name that folder "4287-Jones Corp Brochure." If we're sending the second revision to the client in the form of a PDF, it will be named 4287-jones_brochure_r2.pdf, with "_rx" appended to the end of the file name. We designate final files with a "_f" at the end, so everyone knows it's done. We also place the job number, name, and status in email subject lines to allow for easier searching.

The job numbers go in order, but because of the nature of the business, newer projects may be finished long before older projects. (There's one project we've been working on since last October, but we've finished quite a few in the meantime.) If we need to look up a date, we'll find that on the job's project folder (a physical folder with specs written up on it, and a place to track the hours spent on that particular project.)

In our big file cabinet, we have folders for each client, where we go to look up old jobs if we need to. (This comes in handy when someone needs a brochure, and we can quickly look up how much time we spent on the last several brochures, and give an appropriate estimate based on past experience.) This is where things are sorted by client. If there's an old project we did for Acme Company, we can pull the file from the Acme section, and then pull the digital files from one of the A discs. Which brings me to how we archive digital files.

Our archive CDs and DVDs are organized alphabetically. Once this JonesCorp Brochure is finished, it goes onto an archive disc. That disc would be whatever the next "J" disc is, let's say it's "J-20," which would be the 20th disc in the J section. An ad for Acme Company might be on disc A-8, even though the job number might be 3249.

Does that help?