Roger Zelazny supposedly used to write short episodes of characters’ lives from before or after the story, and explanations and descriptions of background elements (such as the magic/tech you’re talking about) and then destroy them after the main story was written. To get the fractal complexity of real people, who always have more to them than you can see, always just glimpsed by inexplicable but consistent signals, and to restrict descriptive elements of the story to active events - a la “Don’t tell us that the old lady screamed. Bring her on and let her scream.”
I’m not sure how I got to the above paragraph… I wanted to say “don’t work too hard on the details, stories that spend lots of time explaining the placement of nuts and bolts may be fun to craft, but they’re usually boring to read”. The Hobbit is more fun than the Silmarillion.
Since I am not a successful author (well, except in the limited sense of code authorship) my advice should probably not be given a lot of credence. But it’s worth every cent you paid for it! 
