Just out of nowhere:
Keeping a person interested is a balancing act between giving someone enough information to care, and enough mystery that they want to know.
May seem rather obvious, but still. I like to write stuff down (almost seems counter-productive to say that really). It makes it seem solid.
If someone does care, they won't read. But if you tell them too much, they will get bored. So you've go to know where to go to, and where to stop.
Something I have yet to learn, I think :)