How many combinations of tags are there for a file?
There are infinite combinations since you can add your own custom tags, therefore you can have as many tags as you wish and therefore as many tag combinations as you wish.

Organising your files with tags is down to personal preference, but personally I use custom tags for projects and custom-named tags with colour for important/completed/etc.

My current main tag list is as follows:



I usually combine these with the project- or context-specific tag if it is a single file or package, or use the project/context tag on the folder and these general tags on the files themselves.