A few things I did:
1. Arrange Bottles By Use
I have two types of bottles. The big 32oz or 128oz bottles that I keep to fill the little bottles and the little bottles that I will actually hold in my hands while painting. The big bottles simply refill smaller bottles but I have them all in the same space. Solution: I Put big back up bottles in a lower, harder to access shelf and the small bottles of the same materials in the easy to reach shelf. By creating a specific place where I keep second and third bottles or the much larger cartons of a medium, I will know where to look to see if I am truly out of something. This also clears up the easy-to-access space and will mean tripping over multiple bottles of the same thing while trying to grab something else.
2. Dried Out Old Container
I use containers as drying wracks. The heavier the tub the better. So I've been keeping basically empty soft gel matte containers thinking, "Well I need them for drying stuff." But having multiple containers of the same thing is really confusing especially when 2/3rds of them don't actually have usable material inside. I opened them up and am letting them dry. I will then wrap rubber bands around them to indicate their changed purpose. I will keep them in a storage shelf and pull them out when I'm doing a project that needs drying wracks.
3. Combine Materials
I had 3 jars of white gesso. One was 3/4ths full. The other less than a quarter. Using my funnel, I poured them all into the squeeze bottle I now keep for easy access white gesso. All but just a bit fit into the squeeze bottle, and I went from 4 places where I keep white gesso, to one easy to access and easy to use container.
4. Dating Products
When I bring a new bottle of materials into my studio, I am dating it. It's too easy for 6 years to pass and let a product go bad. I don't know what the shelf life of these materials are but it's good to know if something starts to seem a bit strange, be able to look at the jar and say, "Oh right, maybe it's because it's 12 years old." And toss!
I'm not sure I'll stick to it, but it would be great to do this about once a quarter.