genres: Action, Comedy, Documentary, Drama, Fantasy, Family, Horror, Sci-Fi, Suspense, Thriller, War, Western
my sub genres (keywords) is a big list, making it a checkbox field makes it easy to add or subtract as much as i like. i have all of the genres there (so i could have action-comedy or comedy-action) and then a bunch of stuff like 18A, adventure, animation, crime, foreign, ghost, historical, mystery, romance, sports, zombie...etc. it's a long list at this point
this way i can easily assign a broad genre to a film, which is how i normally think when i'm picking a movie
then i can filter it by odd combinations so i can have Action-comedy, or Comedy-action...or Sci-Fi-family-adventure or Sci-Fi-18A-horror, you can just keep filtering down
it's not a perfect system, but by keeping main genres short and simple, i can easily add as many sub genres as i feel like to any given set or subset. i do a similar thing with my music