So I want to start writing a diary style book and have no idea how to properly format it. Now after doing a lot of research for the main book I am working on (still only half way done with it) I learned that formatting is pretty much everything. And I would hate to get it wrong. So if you kind people would point me in the right direction.
There's not one definitive format. I'd be surprised if you haven't already, but type 'epistolary novel' into Wikipedia and you'll find an article with plenty of examples to look into.
I don't see why the format would be any different from any other novel. Minus the "dear diary" tag at the top of course. And that you can format in any way you choose, I'm sure there is no standard.
There are many ways to format an epistolary novel that all work well. You have several tools at your disposal, e.g. dated entries and variations of "dear diary", that you are free to use or not use. The most basic way to do it is to make each chapter consist of one or more entries, with the entries separated by line separators (stars, horizontal lines, or whatever the publisher uses.) Other than that, write it the same as you would write any first person novel. Just be mindful of when and where the narrator is writing each entry and what is happening in the background while it is being written.
