World Building Tips
1. Be anti-monolith: One of the great disservices modern science fiction has done is convince some of us that worlds out there in the greater galaxy are monoliths. An ice world. A desert world. A water world. Reality is demonstrably different - and not simply because Earth has wild variation in climactic zones. Each of the worlds in the solar system demonstrate the same thing. Sure. Mars is red and dusty everywhere. But there's ice at the poles. The equator is warm. Relatively speaking. Even Mercury has wild temperature swings, from 800 degrees on the day side to -290 degrees on the night side. Of course, we can't talk about ecosystems per se, not on Mercury, but we could on Mars. If, someday, humans colonized Mars and began planting crops and trees and otherwise terraforming the Red Planet, there would be climactic zones. Plants would have to adapt or be engineered for different conditions. It's the long way of saying that while we can speak of Europa being a monolith (an ice and water moon) it's likely that most worlds are a combination of many climate types with unique and disparate ecosystems based on an evolutionary history distinct from Earth's.
2. Cultures develop in concert with the evolution of a species: Human culture developed concurrently as humans developed. As an example, caring for the dead is used as a hallmark of culture and is usually attributed to the Neanderthal about 130 thousand years ago. Recently, the discovery of Homo naledi in South Africa pushed the evidence for deliberate burial back to about 225 thousand years ago. The point being that sentient creatures being organizing into societies far earlier than most of us imagine. If a culture in your world does a particular thing, it's likely they've doing the thing far longer than you or your main characters think. It's a great point of conflict if an outsider comes in trying to change some long-held cultural activity. It's an even stronger conflict for someone within the culture to challenge long-standing tradition.
3. Culture often develops in the direction of evolution: This specifically means that when a culture adopts a practice, it is because the practice confers either sexual advantage or survival advantage. Bonus if it's both. If someone within my made up culture takes up regular bathing, they're might gain reproductive advantage because they don't smell or because keeping clean prevents infection giving them more chances to reproduce over time. Another long way of saying that in world building, everything needs to happen for a reason.
Even though the book has been out for several years, I will always recommend Guns, Germs, and Steel by Jared Diamond (https://www.amazon.com/Guns-Germs-Steel-Fates-Societies-ebook/dp/B06X1CT33R) . It is the how-to book on world building because it breaks down the how earth societies and cultures developed. Why some cultures seemed to conquer the world, while other cultures sank into oblivion or where wiped out. It a very handy book in helping prompt world builders to consider how illness, domesticating animals, and developing agriculture changed the shape of humans and of human culture and at what price.
Maybe that's the final piece of world building advice: Everything has a price tag. Magic. Culture. Disrupting culture. Art. Religion. You get to decide what the price tag if for each of those. Even if you're creating your own world from scratch, the laws of physics still apply. The law of conservation of energy suggests that for every expenditure of energy for something like magic, there's an equal and opposite reaction somewhere else. You get to decide what and where.
