I use Avery round labels on top to note the brand, size (5, 6, 8, etc.), nib size (F, M, B, etc.), grinds like SIG, CI, etc. There are rectangular labels that have the same info on the body of the vial.
I have a few nib racks filled with other sizes like Jowo 5, or other types like Bock, TWSBI, Lamy, Retro 51, etc. When I need to pick a nib for a certain pen, I will enter it into the Fountain Pen Companion (FPC). As I mentioned in the FPC article, I use FPC to track my currently inked as well as pen/ink usage. This allows me to enter a pen with a particular nib and grind, which is how I know what nib is in what pen. Then I store the empty vial on the side of one of the racks (along with the other empty vials), until I have cleaned the nib and am ready to put it back inside the vial in its proper spot in the rack.
Pro tip: when cleaning nibs/nib units, keep them next to the pen barrel so you know what nib went with which pen. Pro tip, part 2, don’t put pens with similar nib sizes next to each other so they don’t get mixed up. I will often clean a Jowo 6 nib and then a Jowo 5 nib or a non-Jowo nib before cleaning another Jowo 6. Pro tip, part 3, don’t let your cleaning pile get out of hand so you can avoid nib mixups in the first place (note to self, pay attention to this tip, lol).
All of these little tips and tricks, along with bins and baggies, help me stay organized and able to find accessories and nibs easily. Hope you found some of these tips helpful!
(Disclaimer: All products shown are my own, purchased and accumulated over the past 5+ years in this rabbit hole.)