In science fiction and fantasy, the setting is more crucial than in other genres. Half the point is the place you’re able to dream up!
I’ve noticed a tendency for fantasy to happen in a rural environment. There are journeys through the woods or across the plains. You might stop in a tiny village and save them from bad guys. But there’s often a lot of camping involved. (And yes, fantasy research is the reason for any knowledge I have managed to glean about camping, hiking, and horseback riding.)
Meanwhile, science fiction tends to have an urban vibe. Cyperpunk, of course, is urban, with lots of neon lights. Space stations are like small cities in the sky. You zip around in a hurry, at whatever factor of lightspeed the author wants.
But, of course, it doesn’t have to be that way. And often the most interesting space in SFF is the path less traveled.
I enjoy fantasy cities like Ankh-Morpork and Ba Sing Se. Think about the infrastructure a city might use if magic is an option. You don’t have to be limited to medieval-style cities. What about underground cities, cloud cities, cities in the branches of trees? What if people get around by magic carpet or fairy-dust-driven streetcar?
Likewise, science fiction can take place on planets, deep in the backwoods. What if you were the only human being in a wilderness of coral-like trees? What if you were a colonist, tending a farm that floats on the waves of an ocean world?
Don’t forget small towns. A far-flung spaceport can be an analog to a tourist town. Always busy, but the actual inhabitants are all on a first-name basis, and are there sweeping the promenade when the tourist season is over.
Cities and country tend to feel very different, and not just in the descriptions. Things happen quickly in cities; you can find a body in the morning and have interviewed your top three suspects by afternoon. There’s none of this tedious trudging around. On the other hand, you also can find a sausage-inna-bun pretty fast in the city, which means none of the excitement of being hopelessly lost in the wilderness with nothing to eat.
Consider: how has your character been shaped by living where they do? Are they transit riders, fast talkers, do they know how to do the confident don’t-mug-me walk? Are they used to living among a variety of people and getting the latest news when it’s out? Or are they country folk, who feel that a hundred people is a throng and the next village over is a long way?
Conflict is always born when you put a character outside their comfort zone. Stick that fast talker in the woods, does she know how to get home? When your farmer comes to the city, does he stand still with his mouth open, looking at the buildings?
These are differences many people don’t think much of, because they meet mostly people like themselves. The internet has introduced me to many strange types of human, like “people who have access to Broadway shows” and “people without yards.” Meanwhile I am aware, when I go to the city, how obviously new at everything I am, standing by the metrocard machine trying to figure out how it works.
That rural/urban divide is a big one in the real world; it’s one to consider in your fiction as well.