Best practices for keywords?

[outdoormagic]

Hello all,

I'm looking for best practices as relates to exiftool for keywording. I have searched other sites and there are many opinions, most specific to the tool used (such as Lightroom).

I have a controlled vocabulary. I try to keep nouns singular and verbs as gerund (present participle). Those hierarchical keywords are written to HierarchicalSubject. I then have a "flat" list, essentially (split "|", HierarchicalSubject) written to Subject.

1. Is this a good practice or should I favor other declinations?
2. How do I handle synonyms? Should a write a whole new branch with the synonym substituted or should I just add it to the flat list? Or should the synonym only be a reference in the controlled vocabulary and only the "master" keyword be added?
3. What about other declinations? Should they all be added to the flat list as well?

Thanks,

Paul