I start with the folders. Create ones on broad categories like "Math", "Physics", "Politics", and each of those could have subfolders (folders are called collec

I start with the folders. Create ones on broad categories like "Math", "Physics", "Politics", and each of those could have subfolders (folders are called collections in zotero). An entry can be copied to multiple folders but its copy-by-reference so you see the same file and notes and so on in whatever folder ever you view it. Tags are added as meta-data and I use them for searching the library for things. In a given collection you can select a keyword/tag and it will highlight all items with that tag. I've been using zotero now for years and many 1000s of entries. It's by far the best tool I've used for organizing my stuff.