How to manage publications on a local computer
For the filename, I use a system that I plagiarised from my PhD supervisor:

aaaadd_xxxx_jjj.pdf

where:


aaaa: name of the first author (variable length)
dd: 2-digit year of publication (fixed length)
xxxx: first word of title, minus articles and other small words (variable length)
jjj: abbreviation of journal of publication (variable length, but short)


I then use the same without the .pdf as my bibtex key (with an added :).

For example:

T. Penguin et al, a Survey of Antarctic Leasure Activities, Journal of Improbable Results, 2025

would be

penguin25_survey_jir.pdf

with the bibtex key penguin25:_survey_jir.

I like this system because:


I'm used to it
Filenames remain compact and UNIX shell friendly
The encoded information is usually enough for me to identify the paper


It doesn't cover tagging or categorising.

This applies well to journal articles.  For conference proceedings articles or books, the journal acronym is replaced by an acronym of the conference or the publisher, or perhaps the full name of the publisher; I'm not fully consistent there.  But I don't usually have entire books as PDFs anyway.