For paper documents, I scan then using Scanner Pro on my phone. The phones OCR has become increasingly sophisticated. But the one thing I do do is title the document when I scan it with a fairly descriptive title and month date in the title. To reduce typing and speed up the process of scanning lots of documents, I use the voice typing feature.

For digital documents, I store then in a folder.

Scanned and original digital documents all go in iCloud with categories like - receipts - medical (self, spouse) - taxes - financial (etc.)

I know you didn't ask about photos and music but to me these are also important digital documents.

All photos are managed by the OS in the cloud. I backup the photo database using BackBlaze.

Music is again similarly managed by the OS in the cloud.