Whenever I come up with a city or a country for a story, I just come up with the general characteristics (topography, climate, etc.) But when I start writing in the the setting I keep asking myself not only where things are in relation to each other, but what their main imports and exports are, any kind of geography impeding travel or trade, fault lines that could cause earthquakes, any history of war, conquering, colonization and such. Am I seriously over thinking everything or should I actually write/plan all of this stuff out before I write everything out?
I think not. As an example, if you read Umberto Eco (Name of the Rose or Island of the Day Before being good examples) he designs his locations in intricate detail. Not only does this help with the complexities and continuity of his plot, it also makes for some incredibly rich and compelling settings.
Depends what you're going for. Details for details sake, generally, are too narrow. You want details that function beyond themselves. For ease of demonstration, if your city profited off ivory predominately, then the details are, whether exactly wanted or not, communicating many things (i.e. Heart of Darkness [not the work, necessarily, but potentially ideas related to colonialism, commodification, religious deification of material objects, what have you]). They are multifunctional. Having a mass of information for your settings may be immersive, but too far, it can easily be overloading and unnecessary. I'd ask yourself what the point of these details are. If there isn't a point to them, and the details are rather normal, then you could allow them to rest within the commonplace assumptions of the reader. If I come upon some city, I will assume it has certain systems. If these systems affect some greater idea or criticism you're trying to further, then alter them as such requires and bring them to my attention. Otherwise, I probably don't really need to know about them. Regardless, I wouldn't stress greatly ahead of time. I'd suggest to have a semblance of plan, maybe something informally formal but nothing overwhelming in itself. You can always return and edit and flesh things out if you need to. Don't intimidate yourself into paralysis.
You can never overthink anything when writing a story. The more detail you add into your story the better the outcome will be.
Knowing too much detail can never hurt - just make sure you don't put it all into the actual book and you'll be fine lol. This kinda detail can serve to make things very realistic, and perhaps you're just a fan of world-building and there's nothing wrong with that. I think it's only a problem when planning the setting to such detail is getting in the way of the actual writing - then you have a problem. But this can be easily resolved by giving yourself a time limit on planning/world-building and a date on which to start the actual writing. Time given to research will vary according to the needs of your story - it can be a few weeks, it can be a few years, whatever your novel needs. But as long as by the end of it, you're writing and you have a finished book, do whatever you want.
What genre are you writing? There's more of a tradition of world building in SF/F, for example, than in other genres. I agree with Mckk, though - you probably don't want to put all your detail into the story itself. And make sure you're not planning instead of writing. Like, if you eventually get around to producing something, great, but if all you ever do is plan...
I'll agree that you can't over-think the details of your world, but you could over-write them. Knowing everything possible about the country makes it easier for you to deal with unexpected plot diversions, but we readers don't need to know everything you know.
I tend to agree with Swiveltaffy, just include relevant descriptions, which are relevant to the story. I've just finished a novel set in a small British seaside town. I've only included enough detail to reinforce the fact that it is a small British seaside town. I haven't described the sewerage plant, the gasometer, etc.
I over plan on those details, keep them handy, and use just a few sparse details from them. Don't bore the reader, but know your shit, as it were.
I over-the-counter everything before writing. I usually have something pop into my head, then applies to it something good/bad from our world. Once I start planning something, other things keep forming in my mind, and suddenly my city is alive. It's really helping me develop the scenes, as I know the feeling of the city, and can also imagine it's sounds and people. As I start reading all this will change over time, as my imagination works with it. But regardless it helps me. By knowing how this city would feel and look, how I would like it the first time visiting really starts my imagination, so that I can make the story live its own life. So my tip would be to keep planning all these details out. Just don't stop believing in the story if the city won't stay the way you made it that first time.
I'm using a fictional country as the setting for all my work as well. It never hurts to have it all mapped out somewhere in your head or your notes. Even if you don't need all these details your invented country will feel much more real that way, you can play around with it a lot more and apart from that it's just fun.
World building is something I don't tire of. It speaks to the part of me who enjoys Sim City, Minecraft etc. I love it. But is it good for the writing? As Swiveltaffy says, if its necessary for the story then do it. And if you have the time to world-build like this, then why not? I remember reading a post either on this forum or another that Minecraft was a great way to world build. I had to disagree - it's a terrible way for a writer who has limited time to write: you spend too much time playing games and not enough doing the writing itself. So I guess it's all down to how much writing you are actually doing. There's a balance needed to get that book written just as there is when you are researching one.
You can never know too much about your world but your reader can. If you are naturally inclined to plan out your world in detail then I would go for it. If you have a well built world, it will guide the story and make for a much richer setting. Just don't give the reader a textbook on the history/culture/geography/whatever, a taste here and there as the story unfolds is plenty. On the other hand, don't spend years on the world and neglect the actual writing
I've found using words that work and show my mental image help. It is too easy to go overboard on details though
Best advice I've read: turn your setting into a character, or have the setting reflect a story element. For example, my character is taken to a city. She's grown up in a small village and never seen a modern city before. It swallows her and all the stimulation scares her, bounces her around and leaves her reeling. Then she sees teens from a distance at a Cos-play event and imagines herself among them. All of the setting is my character's reactions, not just a description of things like I started with. A sterile office, a wall of awards but no pictures of any loved ones, a smaller chair for visitors than the chair behind the desk ... A forest still showing the scars of a flood ... And so on
I presume you're not writing about a place that actually exists? So you can just use your imagination? That should be fun. However, I also need to ask ...are you just world-building, or are you actually constructing a story? If you're constructing a story, why not first ask yourself what your story is going to need, in terms of setting. In other words ...will your characters need to travel a lot? If they do, how will they manage this? And how long will it take them to get from Point A to Point B? That's important. I recently read a famous fantasy novel where this notion of distance and travel time was flung down and danced upon. The main character left his school at the end of his spring term, spent weeks getting to a place, several months while he was there, learned a new language, learned a new form of combat, saved 'the day,' met a woman, spent more months in her company, then returned to his original setting ...just in time to resume his fall classes. And no, it wasn't magic or a 'dream' or time-shifting. It was a dreadful oversight on the part of the author, who hadn't done a very good job of planning distances and the time it took to get there. Does history play a huge part in your story? If so, you'll definitely need to construct it. Are your characters going to need a place to hide away from the world? If so, make sure you construct a few of those as well—either within urban settings, rural settings, or wilderness. Do your characters require a kingdom? An office? A battlefield? A hospital? Does your story need lots of rain? Snow? Heat? Desert? Will one of your characters drown in a river? If so, you need a river. Etc. Keep asking yourself 'what does my story need?' as you construct your world. That way you won't miss out on something vital, or worse yet, end up pulling something unbelievable out of the air, just because your plot requires it. This can happen in fantasy as well as any other genre of writing. Everything has to make sense on some level. Once you have all your necessary settings in place, then have fun constructing more details, histories, interconnected events that make it richer. Just keep in mind you're telling a story, and use these these details to underpin your story and give it life and colour. Beware of infodumps, which will lurk nearby in this scenario, and don't let supplementary information swamp your story. The best way to present a world is through the eyes of your characters. Let us see what they see—and how they see it. Give us their opinion on what they see. Let us know (through what they say and do) what they think of a political situation, or the place they are forced to live, or the journey they are about to take by sea, or what they think of other races and cultures that make up their world. Don't tell us what these races and cultures are like. Let your POV characters do that for you.
I won't repeat the many comments above which I largely agree with. I will just add that it depends on what you need. For example, I found it useful to draw a map of the protagonist's home area, even though most of the story takes place in hospital, and other worlds accessed via the hospital. However it gave me a picture of her usual daily routine. I'm discovering that visual references are very useful to me. However, that's just me, it's a personal process. Do whatever you need to get the job done.
You should definitely plot out all these things. You don't need to tell the reader all this information (in all likeliness, you'll probably only need to tell them 25% of it) but it's important, as the author, to know all this stuff. Makes it easier to come up with compelling characters too!