A thought on worldbuilding, and different ways to approach it.
Some world building is just that – you’ve got to lay the foundations, do the planning. If you want to write a story about miners fighting kobolds, then read up on mining, on geology, on folklore. If your story is about, say, electoral politics in a quasi-Victorian fantasy city, then you can read up on electoral politics and Victorian cities. If you’ve want a story about a war, then you need two factions who can fight; if you want a dragon who kidnaps princesses, then you need (a) dragons and (b) some sort of ruling arrangement that produces princesses. Worldbuilding that’s absolutely foundational to what your story is about (or to be precise, what you think your story is going to be about before you write it) has to be done in advance.
Other world building, though, can be on the fly. Think of it as an ornamental flourish at first- a quirk of your setting that adds distinctiveness without changing anything significant. Every so often, throw in some twist or bit of weirdness. Elves can see through the eyes of cats. The gods speak in thunderstorms. Swords are made of wood, not steel. You don’t need, at this stage, to have any idea why that flourish exists, or how it fits into the story. Just grab whatever’s cool, or quirky. Slam ideas together – take inspiration from what’s outside your window, or on tv right now, or a random wikipedia article (Literally – I just clicked here and got irrigation in viticulture, and now I’m thinking about how you’d cross that concept over with vampires and dragons and the like. Vines irrigated with blood for vampires to drink. Wizards spilling dragon’s blood to create enchanted vintages…)
Now, perform some safety checks.
First, look at how the change might impact your planned story. If your story is about an elf, then “elves can see through the eyes of cats” has a big impact, and you’ll need to carefully think through the implications. If a worldbuilding flourish looks like it’s going to require a lot of work to integrate into your story, it’s probably too much trouble – consider killing it. You don’t want to make things harder.
Check #2: Run through common ways people interact with the thing you’ve just changed. God-talking thunderstorms are a simple twist – it’s really just taking divine revelation and adding a little reverb. Assuming there’s already prophecy and divine revelation in your world, then this won’t impact things.
Elves who can spy on you through cats is a bigger change – depending on how common elves are (and how common cats are), how people act around cats would be very different. Would you keep a cat in your home, if you knew some elf could be spying on you? (Then again, Alexa). Would every elf have a cat? Does each elf bond with a particular cat?
Where do wooden swords come from? Are they grown? Do they occur naturally, or is it some magical form of gardening? Does everyone use wooden swords, or just one particular faction?
If neither of the above checks shows up any problems, keep going. As you write, look for ways to refer to your flourish or its second-order effects. You can do God talks through thunderstorms? All right, then maybe priests talk through metal tubes to get the same divine voice. Maybe mystics chase storms. Or maybe those hermits who sit on pillars in the desert sit on lightning rods instead. Look for ways to point back at the flourish, to build on it.
If elves can see through cats, then maybe thieves kill cats to ensure they’re not being spied on… so a thief’s house is full of mice. Maybe harming a cat is forbidden in elf-land. Maybe old elves use cats like spectacles, and you can describe a cat reading a newspaper while a white-haired elf turns the pages. Maybe there are cat-couriers who bring the eyes of elf-princes across the land.
If swords are wooden… then if you impale someone with a sword. does the sword grow into a tree? Are old battlefields like orchards? Or is fire a more common weapon, to ignite your enemy’s weapons? Is it only swords they make out of wood, or can other weapons be grown the same way? Why would anyone make a sword out of wood to begin with – why not metal? Do swords swell in the damp unless treated, and you’ve got soldiers varnishing their blades instead of whetting them?
Sometimes, you’ll realise that a particular worldbuilding flourish gets in your way. It might break your story in a way you didn’t anticipate, or just take up too much time for what’s effectively an aside. That’s fine – the whole point of a flourish is that it’s an ornamental feature, not loadbearing, and can be dumped without any remorse. Be ruthless.
And when it comes time to revise and edit, you’ll often discover that what started out as a flourish actually fits perfectly into the setting and story, and becomes a foundational element. We’re pattern matching critters – add an unexpected or even random element, and your brain will naturally look for ways to align it with the rest of the story. Trust your subconscious to do the heavy lifting of added worldbuilding for you…