“I’m going to write fantasy,” I announced, with all the confidence of a fourteen-year-old who hasn’t thought it through. “Then, if I don’t know something, I can just make it up. No research!”
“Hm,” said my dad, with that parental expression of unimpressed but trying not to discourage.
He’s not a writer, I thought, what does he know?
Turns out, more than I do.
To write convincingly, whether fiction or non-fiction, you have to know your subject matter. It doesn’t matter if you’re making it up or not: you still need to know it, inside-out and back-to-front. You don’t need to have experienced it, but you do need to be able to research it, and to be able to imagine how it feels.
And yes, in the grand scheme of things, if you don’t know or can’t find something out, you can just “make it up”, but make sure it makes sense with the rest of your story. And you’ll have to know how it fits in.
My suspicion, based on my current WIP, is that the key to this is Proper Planning. That way you don’t get sudden surprises half way through a chapter. And you don’t need to rewrite the entire manuscript.
You have to know what you’re writing about, whatever that is.