If I play a game just for the story, I'll go for easy. Otherwise, I go for normal, then increase that if I want to play it again later and thought it was too easy.

I don't often play games just for their story though. That would usually only be if I'm playing it because I in reality want to play its sequel, and just want to hurry through the first one.

It can also happen that I select easy in a type of game that I am very unfamiliar with, although the number of such games is pretty low at this point in my life.