The onion method by Lourenço Soares
Lourenço uses a very interesting method to write the stories of a feature. He named it the onion method.
Basically he writes at the top of the canvas the name of the feature, theme, or epic. Then he puts in the center the most basic story; that simpliest that can be coded with hardcoded values. For example unauthorized login (hardcoded; the login always fails)
Then he draws a layer and asks the participants what are the next set of stories increasing the core of the onion. Sample stories for that layer would be: userID validation according to DB registered usrs. User validation with userID and password. Only IP addresses within the authorized range.
Then he creates a new layer and repeat the question. Other sample stories : Password reset. Sending e-mail with a link to reset password. Advanced data security logging.
Below is an illustrative photo of the method.