one of the most important things about writing is actually knowing what you're writing about.
there's nothing worse than reading a book who's main character has something like insomnia or other similar things, because the author wanted the character to have a quirky trait or difference and then seeing the absolute lack of affect the issue has to the persons life.
for example, running with the insomnia idea, if you read a book like that and then the next day the character woke up at five, went for a run and did all their grocery shopping, you'd be nothing short of confused. its the same with writing about anything, though - do your research. if you're writing a story in the world of 'mistborn', don't rewrite the world just because you don't know where things are, or if you're writing about the batfamily, don't just dismiss character that could be really good for the plot if its just because you don't know too much about them.
sure, alternate universes are incredibly fun to read and even more fun to write, but if you want to include something then do, don't half-ass it and skip over things. trust me, its so much more fun when you know what you're doing.
- urbandrakes