IIRC, you're on a Mac? In that case, I think tags would probably work best. You can apply multiple ones to selected multiple items pretty easily from the Finder and search for them, and if you've got decent Terminal skills, I'm pretty sure there are command-line tools to interact with them floating around on Github.
IMHO a few advantages of tags over file renaming include:
- ability to assign different colours to different tags; a file given multiple such tags will show the little coloured circles overlapping, so you can easily see combinations
- in Finder List View, you can set Tags as a View Option, and also sort by tag
- you don't have to mess around manually renaming files (or feeding them through a file renaming app), whose names could get unwieldy and difficult to easily display if you end up appending a lot of stuff
- ability to mass-rename/re-colour a particular tag if you decide it should be somehow different
- can add favourite tags to Finder quick-apply box and show them in the Sidebar as well
Potential disadvantages vs renaming:
- maybe not as easy to see upon first glance in Finder what the status is, if you're on Column or Icon view
- not really portable to other systems in case you have to work on a Linux or Windows machine or share with non-Mac users
Anyway, that's how I arrange my ebook folders on my Mac (tag statuses for Read, translated from a particular language, did I fix the typos, original file is DRM-free, extra backup exists of non-cloud store purchase, etc.) and maybe it'll be useful for you.