There's one big rule in storytelling:
Only tell stories you love.
Sorry, didn't mean to shout, but it's very important. If you don't love the stories you tell, your audience won't love them either. If your audience doesn't love the story, they will let you know in subtle and not-so-subtle ways, depending on how old they are.
It seems obvious, doesn't it? However, I've had experiences where I've tried to fit a story I only sort of liked into a program. It doesn't work.
Once I was performing in a library and the librarian asked if I would tell The Wide-Mouth Frog. I know this story, but it wasn't in my repertoire and it isn't one I love. Still, I wanted to please the librarian, so I told it. It was flat. Boring. Excruciating. It's a good story, just not good for me.
Sometimes storytellers try to shoehorn a story they don't love into a program because it fits a theme or is from a specific country. It rarely works out.
This is one of the few times I'll exhort you not to do something.When you tell stories you don't love, and you do a mediocre job, it reflects badly on your skills as a storyteller, on other storytellers ("Oh, we had a storyteller once. She wasn't very good. We don't hire storytellers anymore") and on the art of storytelling. Please, don't do it.