One especially interesting aspect of this whole book-writing process has been how many tiny things there are to learn. There are big questions, of course - like how to write a book proposal at all, or how to get it into the right hands once it's written - but there have also been a million smaller ones that I never anticipated. (I was nervous about all of them, just so we're clear; Ye Olde Type A tendencies have been out in full force for the past several months.)
As an example, I didn't know whether I should be sending my editor chapters as I finished them, or whether that was annoying and I should just send her the whole thing when I was done (the latter was preferable, as it turned out - at least for my editor). I didn't know whether it would be helpful if I bounced ideas back and forth directly with the illustrator so that other people didn't have to act as a go-between (apparently that's a big "no": it's the art director's job to liaise between the author and the illustrator).
Basically, I didn't want to be a pain in the ass. At all.