Craft Without Clutter - Tips for keeping your art supplies organized

First of all, volume. Some of the suggestions talk about relatively small storage solutions.
Yarns come in varying sizes and shapes (hanks, skeins, balls and cakes), and as you use it, the size varies even more. How do you organize yarn? By colour? By weight (yarn weight = how thick is the yarn)? By composition? (Acrylics sharing space with alpaca? The horror.)
Most yarn crafters will have several projects going at once, at varying complexities and with varying needs. Keeping all of the supplies for a single project together, is a task on its own. I, for example, currently have mittens, scarf, shawl and baby blanket all in progress, at varying stages, with varying needs, so need a different kind of focus from me. Some require careful calculations, and I'm not always in a focused enough space for.
The shawl is just waiting for a nice border and blocking, the lace scarf is waiting for me to decide on the appropriate cast off to keep its shape, the baby blanket is long and repetitive so I needed a break, and the mittens are currently on my desk and I work on them as I go along.

And usually there's a "I f-ed this project up, and need to frog back to a stable state before I can go on, but the project is now on time out".

And then we get into the varying required supplies.
Crochet hooks. Tunisian Crochet hooks. Knitting needles - Double pointed, regular or circular? Metal, plastic or wood? Long needles, for projects like a blanket, or short needles for socks, or maybe an in-between for in-between projects?
Stitch markers of varying types or colours. Working on a more involved pattern? Stitch holders. Row counters. Scissors. Spare yarn for lifelines. Tapestry needles for finishing/lifeline/various functions. Working with interchangeable needles? Cables of different sizes, stoppers, pins for screwing the cables into place.
Making amigurumis? What about safety eyes. What about washers for safety eyes? What about embroidery thread for details? What about fibrefill???

Some of these things are big and long. Some of them tiny and can get lost. Some of these you only need one, some you need a large supply.

Oh, remember those hanks? Yeah, they need a yarn winder, and also the umbrella thingy to keep them in place while you work the winder.

Oh, and blocking mats for big projects, and a blocking board because it's easier for granny squares, pot holders and smaller projects.

Working on several projects at once? Project bags to put all supplies for one project in one place. I actually have little pouches with most-used notions that I keep in each project bag, so I don't have to keep looking for the one and move it as I change projects.

So yeah. I have a craft closet, and it's packed. And messy, but I know where things are in the mess, and if I don't, I have duplicates. :)