I enjoy adding a few details that are ersatz, slightly off-kilter, and meaningless. Life is confusing, and sometimes we don't know how to feel about the random things in it. Sometimes odd details can add a layer of verisimilitude.

As for actual lore, in my rough drafting phase I tend to refer to things spontaneously. A pumpkin plague, a pre-modern fallen empire, an ancient grudge. Then I go back and make sense of things, and with enough careful work I find I've somehow managed to generate enough jigsaw pieces to form a picture. I edit out what doesn't fit, later on when I'm sure I have everything I need.