What I’ve learned (so far) while writing my first novel

I have written my first novel. It’s the first part in a fantasy series that will have, at least, two parts and, probably, a prequel, because is it even fantasy if it’s just one book? Anyway, my book is currently being read by some kind friends, before I finish it off and publish it, so I figured I might as well share some of the things I’ve learned so far.