Blog-reader and blogger Mark Harbinger emailed me to say one comment he gets from alpha-readers "is them dinging me for 'breaking the fourth wall'," when he goes for "meta-narration in first person": i.e. a internal narrator, telling a story which includes themselves, who sometimes talked directly to the reader. Paraphrasing his example, you might deliberately choose to open a story like this:
I always say that "Make hay while the sun shines" is only a useful maxim if the sun above you ever does shine. And in my dungeon, it doesn't, and it wasn't shining on that Thursday.
The idea of the "fourth wall" comes originally from the slow evolution of the proscenium arch theatre from the 16th century onwards: the architecture of indoor theatres increasingly separated the humans representing characters-in-action on stage, from the humans who'd come to see the story of those characters being re-created. When cinema arrived, fourth-wall thinking came very naturally, not least because the characters-in-action are not in the same room, thanks to their shadows, the screen creates an illusion that it's a wall beyond which all this is happening. Over centuries, audiences increasingly wanted and expected to feel that they were watching real, individual, one-off events happening before their eyes, and this shift towards realism and naturalism parallelled what had been happening with the novel.
1) Prose narrative is not drama, and a novel is not a film-script. Even if you're sitting in a room with the writer speaking their work, the words themselves are still telling of something that happened elsewhere (and, by definition, at another time: more on past vs present tense here.) However magically the writer's and reader's brains conjure up that other place and time, there is no inbuilt fourth wall to the experience. There is only a (usually silent) negotiation over how much writer and reader acknowledge or ignore the contrast between their shared space, and the otherness of the purely mental story-space. Even in print or recorded audio, there is a reader at the other end of your act of storytelling, and your choice is simply whether you want to acknowledge and work with their existence, or ignore it.
2) Why not let your narrator talk the way storytellers always have? Why not let a character who is narrating their own story talk directly to their audience, not just at them? It’s a much older way to tell a story and it's not surprising that first-person novels are so often formed as memoir or diary: explicit acts of storytelling. It's arguably more natural than the "naturalist" illusion that the main character is talking to themselves and the narrative is just seeping into the reader's brain by osmosis. Of course, we've got so used to the latter we don't think of it that way, but there's still plenty of the former about, for example in commercial women’s fiction, where the tone is so often of the protagonist telling their story to a girlfriend (who, it's implied, is the reader) over a glass of wine. And to whom is Raymond Chandler's Philip Marlowe saying "There are blondes, and blondes and it is almost a joke word nowadays"*, if not the reader?
3) The key is to do it wholeheartedly, with confidence and consistency, and take care to create the reader you need early on. Together, starting early and doing it with confidence help the reader settle into reading the way this story needs to be read. That's particularly true if you're working by older or different traditions from the current late-20th-early-21st literary creative writing tradition: if there are just one or two instances of addressing the reader - particularly if they're late in the book - it’s more likely (though not inevitable) that the reader will be wrong-footed, jarred out of the stream of the story, feeling abandoned and dissatisfied, and so ultimately unsatisfied.
*In The Long Goodbye