What you do and do not do.
One panelist brought up fairy tales without any magic. Another panelist didn't think there were any. There are. Till Eulenspiegel, the first example brought up, is ambiguously a fairy tale, but Catskin and Cap O'Rushes are clearly fairy tales because they are clearly Donkeyskin variants -- or Cinderella ones.
I brought up that most retelling are of a tiny handful of tales. There are a plethora that are seldom touched -- I once read a story by Patricia McKillip and thought, Ah! The Singing Springing Lark, and even at this panel, only a few people recognized it and it's one of Grimms' -- and then there are those you can't retell because -- Catskin? Tattercoats? Try to retell one of those and people will assume you are telling Cinderella despite the obvious differences.