I have long struggled with storing my leftover yarn. I've tried everything from plastic bags, to pretty glass containers for decoration to fabric bins. Every time I would need a little leftover yarn I was throwing tiny balls of yarn everywhere looking for the right one. I've finally come up with a solution that's working for me. Turns out when you decide to label things, it's easier to find things.
I design and knit with so much fingering weight yarn, this system is currently working for me. I imagine that over time I will need a bigger fingering weight bin and will have to separate the "not fingering" bin. I also have two other bins of leftovers in my office - for my third and fourth books that are currently in various stages of production. Once those books come out I'll add the yarn into the bins above. I like keeping the book yarn scraps separated just so in the unlikely event something goes wrong with a project I can locate the yarn for it easily. It hasn't happened yet, but I'd like to be able to find the right yarn quickly if I had to! :)
Keeping the fingering yarn scrap stash under control has been pretty easy. I use it a lot of swatching, and I also let Cathy have a dive in there every now and then. She's working on one of those sock-yarn scrap blankets and likes looking for a mix of colors. I'm happy to help!
How do you store your yarn scraps? I'd love to hear about your storage solutions!