Over the past few years our filing system has become nearly paperless. In the past, a large project might have generated anywhere from four to 12 three-inch-thick binders of paper.
The old process used binders with tabs for the various topics that we always encounter - Site, Codes, Budget, etc. It was about as easy to file things as using manila folders, and it was much easier to retrieve things.
The new system mimics the organization of the old system, but we use nested folders on the server to file the content digitally. It is easier to file and much easier to retrieve information.
Here is how it works.
Many times you won't have paper at all. For example, draft a proposal; when complete, turn it into a PDF and email it to the client. File the electronic original. I often print a draft to proof/markup, but I don't save a paper copy.
There is no real point in trying to avoid all paper; just don't file the paper.
Besides taking less time to file and retrieve, the electronic files don't take up floor space, and don't take longer and longer to find as time goes by.