Except of course keeping them in mind. There are a lot of them to juggle.
Especially if you try to write more than one story on that vein and not repeat yourself.
Well, the rule is, I've decided, to not repeat a specific tale, but repeating types is fine in different stories. I've still decided to do some research. Fortunately the rule for that is simple: read a big book of fairy tales. "Fairy Tales of Region" is generally a reliable title for a mix.