TIP 3 - Storing paint tubes.
When I switiched to using water soluble oils, I found some good deals on Ebay so ended up with a lot of tubes to manage. The solution - 1 1/2 inch tall stackable plastic storage bins from the home supply store. These are just tall enough so tubes can lie down and yet they will stack. I keep a bin for each major color group and when I start to run out I just pop a new tube out.
Some of the tubes, as they get old, tend to harden up. I solved this by buying some empty tubes, then cutting open the old tube and adding a little medium to soften the paint again to a buttery consistency I like, then stuffing the paint into the empty tube. I often do this with white as I tend to use a lot and buy it in larger tubes, and even new tubes at times are too stiff to use well for mixing. I know some folks in our group buy some colors in large cans and use this process so small tubes are ready to carry.
Photo above is the storage of my multiple tubes while below is my cart where I keep the tubes close at hand in several of these bins.
Note in the lower image the canvas pliers, which work great to squeeze the last vestiges of paint from a tube, and the tube wringer, top right, that I use along the way to keep the paint fresher and used tubes smaller to carry in my paint boxes. Comes in handy for the toothpaste tube too!
Canvas pliers, hammerhead shape, and tube wringer, the metal square object.