So as I have said before I have been collecting poser stuff for a long time ( I began in poser 3)  and while I don't have everything I have collected in the computer, I do have enough to get lost from time to time and spend ages trying to locate something not remembering if it is a prop or a character? Clothing is not a problem I have developed a wardrobe system based of the figures. However room, architectures and the list goes on, it can get very confusing. How do you people store your things? if I stored things by vendors would that make it harder or better? 

Here is my list of runtimes.
_installations is used to unzip what I buy online, as I always keep the additional materials with the main character/cloth/Whatever prop.
Same organization for the Zip's/Exe's bought online: always under the name of the item, on my NAS.

In my case, Props keeps everything that's neither landscape-related (thus the  Landscape runtime) nor a human/animal nor a cloth, as they all have dedicated runtimes.
Some are old runtimes that I don't use anymore but keep there just in case.

Special case #1:  Poser 7, which inherits the complete dis-organization provoked by  keeping the original vendors' folders.
Special case #2: Dawn which is naturally nicely organized

When I'm looking for something special, I often use Poser's search function, which could be seriously enhanced, as it's based on a database system. But sometimes, it down not work or the result are too numerous, in those case I use Voidtools' excellent Everything, to search either in the runtimes location or in the original vendors assets