I like to store my thread in the closet because they are out of direct sunlight - which leads to deterioration of the thread over a long period of time. Some of the serger spools, I have owned for quite while.
Here's the rack near the ceiling. I need a little step stool to access the ones nearer the top, but that's ok. The step stool tucks away nicely in the closet as well.
Another idea for thread storage is to use the nuts and bolts bins like I showed in Tip #5. I store all of my rayon machine embroidery threads in the top bin. On the bottom, I have some very small spools that fit just perfectly in these drawers, alongside some more beads and larger buttons.
This concludes my series on sewing organization tips. I hope you have found them to be useful and will try a few!