We've heard the high tech, the low tech, and the laughably sublime. We'll share them.
Find it – high-tech style: Drag out your laptop and your choice of software programs. For those of us who are into words, a word processor is probably enough. If you're a big time fan of spreadsheets or database programs, you know where to go.
Now, number your outside storage compartments in some sort of logical fashion. Take inventory of all the stuff you have squirreled away in those compartments. You can add numbers or identifications for inside closets, drawers, and cabinets.
Add the "stuff" to the list, identifying the specific storage location. If the list is really lengthy, you can use the "search" function to narrow down the item you're looking for. For example, "brush," could cover a lot of ground, but it'll get you there. How about, "brush, gas grill," or "brush, awning cleaning," or "brush, refrigerator flue," or even, "brush, hair" for those of us who still have a need for such a thing.
Find it – low-tech style: Take out your pencil and paper. Draw a map of your RV and add pointer lines. In small, tiny, hard-to-read-without-magnifier writing, write whatever it is that you have in each compartment, closet, drawer, or cabinet. May require a few pieces of paper, depending on how big the rig, and how much stuff you have.
Now the real problem: Put your list away in a place where you won't (repeat, won't) forget where the list is. Sooner or later you'll have two or more copies of the list, for all the times that you lost it, and later found it again.
Find it – likes alike style: One RVer says he doesn't worry about computers or lists. He puts his stuff away like this: "Tools, in the tool bay. Cleaning supplies, in the wet bay. Other stuff bays."
Then there are the folks who take the industry slogan, "Life's an adventure, go RVing!" far too much to heart. " I do not organize and do not make a list. I like the hunt. And of course, when I cannot find it, I buy another. That is why I own at least two of everything. And buying another means I then find the first that I could not find before. By the way, has anyone seen my Craftsman 3/8th drive socket wrench?"