I’m actually glad you did, I’m going through my system as I cahnge major tools and revisiting tagging is an important part.
First off I am not generally a tagger of files I use tags in specific applications where they serve a specific purpose. Tags on files do not carry across all operating systems so I don’t use them.
Before you can come up with a list of tags think how you will use them. Are they for process, for location, for subject, for time sequence or something else?
Think about how you first start to look for something that you know you have but can’t find.
What types of things do you use for searching?
For example: My Lightroom database has several sets of tags, one is based on process, where in the photo intake process I am so that I can easily pull out photos that have a specific next task to be done on them. (@needsKeywords, @needsName), Another set is based on Geography, loosly based on the official geographich placenames database geographic names but hierarchical with country, state, city, address or feature as the tree. (United_States/Colorado/Paonia/Garvin_Mesa/red_barn) Another is taxonomy of the animals (ANIMAL/ovine/domestic_sheep/Breed_BWMS/Desert_Weyr_Tiberius)
For files I don’t tag, I use locations in folders to find them but they could easily be tags. So I have Bank_Statements-Personal or Sheep-Guard_Dogs as folders and the files are there.
Where I am really starting to use tags now is in Obsidian.
I use tags for status on projects (project/active, project/archive, project/hold) for contexts on tasks (Context/OutsideWithHelp Context/Phone) I have a few I use to gather notes into a group (emergency, Household_Inventory) with MOC type notes that pull those items together in a list of documents using dataview queries.
I use Hazel to move stuff into folders but I don’t try to tag anything using Hazel.