I've arrived at a bit of a stumbling block: the main character finds a children's picture book that offers a lot of exposition into his world's mythos. Hopefully, this inclusion will pay off and clue the reader into many important plot elements. I remember Orwell doing something very similar in 1984, when Winston reads 'The Theory and Practice of Oligarchical Collectivism'. The problem is, it wasn't very good. I hope to avoid the same mistakes I feel Orwell made, and some points are already obvious. Don't write for pages and pages and pages, and don't outright dump information but allude to it instead. But it still doesn't seem like enough. I've tried to abridge the text in the children's book to a very short length, but it has the exact opposite effect and feels far too short to be substantial enough. It occurs right after a huge chunk of exposition as well, so if I pad it out even slightly the reader will probably be bored to tears. My main point is: how do I pull off this story-within-a-story technique without being overly obnoxious about it?
This won't be strictly applicable because you are writing children's story, but maybe can help. My favourite story within the story is in Anne Rice's 'The Witching Hour'. Generally speaking, I've seen this done in different ways, you can show a character finding someone's journal or letters (like in 'V for Vendetta'), records of surveillance, historical records, military interview records (Murakami does this well), or you can have a subplot, anywhere from 5 to 20k words usually works peppered through the novel, in which you can explore your other story, which can be in different time, style or POV. So you can 'show' it, by using ordinary narrative style with scenes, summaries, dialogue etc, like a small story in three acts, or you can make it quite journalistic in terms of 'telling' or recounting events for the reader, if you wish, gives it a sense of non-fiction that sometimes works better.
Thanks for the suggestions! I'll definitely jot down the name of those authors and texts so I can look at them at some point. At the moment my mind isn't drastically changed, but this IS a first draft. I'll be sure to edit it a thousand times in retrospect!