Here's how I work with worldbuilding (and backstory):
- Use as little backstory and worldbuilding information as you can get away with
- Let the story tell you when information is needed
- Include information implicitly, hidden in plain sight, as a tone or air in the scenes rather than explicitly "on the reader's nose"
- Save the guide books and other supporting literature for after your books have gained a readership that wants them
- Keep your information in a safe, ordered place, to know this information is safe even if it's not included in the novel
- Keep a "darling file" for what you delete, so you can feel safe that it's not lost forever...
Use as LITTLE worldbuilding and backstory information as possible
Never use more backstory or worldbuilding information than needed, than the POV-character knows and would need to think about at any given time.
People are OK with a world that isn't fully explained to them. Almost every given name and every city name in the world has a meaning. But we're OK with Paris or Robert without explanations because we're used to them.
If your characters (and narrator) uses worldbuilding information with the same authority we use Robert and Paris, the reader will recognize that as being part of the world and would not require more explanation than that.
It's a name, it's a flux capacitor, it's a deuteronic frombotzer, no big deal!
Let the story tell you what information is needed and when
Trust the story to reveal when more is needed.
I once wrote a story in deep POV where I was sure the main character's parents would forever go by "mom" and "dad" and I was okay with that. About halfway through the story, the need for their real names did arise anyway, so I could use the first names I've given them. But before that point, I felt it would have been artificial to do so. The needs of the story told me when to use that information.
Another example. Your character's apartment. When they enter it after work, they may not notice things in it at all. However, if someone is coming to visit, anyone from mom to a hot date or friends or whomever, your character might start noticing details (usually in need of fixing, a.k.a. cleaning up...) ;o) Still the story, the character, and the relations inform what information is needed or will be detected by the POV-character.
If you don't need the information to tell the story, does your reader need it to understand your story?
Include backstory and worldbuilding information implicitly
Backstory and worldbuilding information should inform your descriptions of your world and characters implicitly.
Imagine a barn. (Or google up a picture of one). Take a minute or two to describe it.
Have you done that? (Ok, maybe you don't have to, to get my point, but if you want to, go ahead and do it now...)
Now imagine the same barn, but this time someone important (e.g. the narrator's dad) has hanged themselves in the barn (we can't see that from our vantage point). Describe the barn again. Without mentioning the hanging...
Still, any difference?
That difference is how backstory and worldbuilding should be implicitly included in your descriptions. As hints and word choice rather than on-the-nose info neither the character nor the reader needs to "get it".
Hide this information in plain sight...
Guide books, supporting literature
How about guide books and other supporting literature?
I think if it is needed to understand the story, it should be in the story. These books are there for the dedicated fan, and maybe they create a deeper understanding of the story, but I think they should never be required to get the story. Rather, I think part from satisfying a fanbase there are also economic reasons behind their existence.
Keep track of your information
So, what to do with all that worldbuilding and character-building information you've created?
My suggestion is to use a wiki to keep track of all information or any other tool other than the actual manuscript. This way you have it at your fingertips and can use it to get the right "tone" in your scenes, but you know you have it in a safe place, in a good structure so you can keep it there... maybe for the world book you will publish after the novels have become a smash hit? ;o)
When you find something that you need to delete, you can make it easier to do so by keeping a "darling file" where you cut and paste this information... if you should need it in the future...