I've been developing a fantasy universe for a while now, about two years. I'm at that point where I need to add all those tiny details that are necessary for making the universe credible - that is, details like how the economy works, what sort of police force it has, etc - but, I'm having trouble coming up with what those details are (not so much about coming up with their actual content). I've been told by several people to check history books and such, but I don't know what to search for so I'm still kind of lost there.
You can find all the information I have developed about this universe at https://docs.google.com/document/d/1XK9nRByKCZfcX59lm6d0TCQfJmsK_eP1EIech1u5ayE/edit?authkey=CN34wYMM&authkey=CN34wYMM
Hopefully this will explain my problem properly: I have no trouble deciding these details, but I have trouble thinking about which details to include. For instance, a friend of mine suggested the police force detail, but before that I had no idea of that detail to include.
I was hoping to get some help to figure out which details I should include to make this feel more like a living world rather than something artificial, any help is appreciated!