Darkrooms, studios, closets and basements are messy places. Water, dust, humidity and other damaging factors can easily destroy negatives. Having a system for categorizing, storing, and preserving your valuable negatives is more than a good idea.
There are many ways to protect and file negatives. The most popular ones are the clear sleeves that you see hanging in packs of 25 or 100 at your local photo store. They come in a variety of sizes to accommodate any size negative. Sleeves can be made from various materials such as polyester, polypropylene or polyethylene. Polyester sleeves are the most costly and are most susceptible to dust. Polypropylene sleeves are firm, very clear material renowned for stability. Polyethylene is also a stable material but not as visually clear as polypropylene.
Once the negatives are stored within the sleeve, the sleeve itself can then be filed inside an archival binder or box. Just as with storage sleeves, there are many kinds of binders available.
When you begin a printing session and need to access your files, it might be a good idea to sort through the negatives that you want to print and set them aside outside the darkroom. As you finish a print, re-store the negative to its original storage sleeve and take the next one in.