1st try to minimize the number you maintain. Many times organizations maintain an MSDS for a "consumer commodity" material, resulting in documentation overkill.
You next need to evaluate employee access to MSDS's. CalOSHA has an undefined time requirement of 15 minutes (I've been down the CalOSHA trail more than once when I was doing EHS in CA). Develop a system that enables employees to "readily" access an MSDS, whether electronic or hard copy.
I've found the simplest method is to generate an alpha-numeric system with each material having a unique number. The alpha part can be used to identify the type or area usage (if only used in 1 area) and the numeric is self explanatory. Materials used in process or by employees have to be labeled, so as part of the routine each material, lets say can of paint or bottle of giz, before it is dispensed or issued, is tagged with the unique number. Presto, bingo, there it is.
File your MSDS's under the unique numbers (set up a spreadsheet maybe) and there you go.
I'm currently using a similar system on my hazmat here. The information I gather from the unique identifiers provides me what I need to do my monthly mass balance calculations for my Title V permit, TIER II reports, and SWPP management.