I have new parts are organized in drawers according to what they go to (pop bumper assemblies, flipper assemblies, switches, etc)

Used parts go into boxes that are labeled according to game system (gottlieb system 1, gottlieb system 80, classic bally/stern, etc). Electronics are in their own separate boxes labeled by game system as well. Each board is in an anti static bag and wrapped in bubble wrap.

Game specific stuff get puts into its own box labeled with the name of the game.

Parts that I've replaced that aren't broken, but am unlikely to use because of cosmetic isssues, get tossed in their own box as an "emergency stash" to use as a temporary replacement just in case I don't have a new part on hand in case something breaks.

Small parts, like connectors, pins, resistors, caps, fuses, mostly go into sectioned parts orgainizers.

But...I'm always organizing and resorting things depending in what's coming in, what's going out, how to use the space I have as most effectively as possible, and what helps makes things easier to find.