Watch lots of movies and read or listen to a lot of books. Also read some of the more scientific and speculative sites and forums.

Basically practice, practice, practice.

I like the theme of no electricity. What if the sun and earth kept flipping magnetic poles. How would this affect electricity which depends on magnetism. What if the strength of earths magnetism was peaking up and down effectively making electricity unreliable. Could we develop a completely mechanical world? What would happen to communications with out radio and wireless. Are we back to letters and long distance communications taking days or weeks by plane or boat? Could we develop a chemical laser for long distance communications without the means to modulate a signal with nothing but mechanical means? How do we shutdown nuclear plants gracefully without electric pumps? We could resort to diesel and steam engines but a lot more labor would be involved for monitoring. Do we use punch cards, type writers and maybe automated engines to drive mass communications or instructions like a piano from the 1800s that played itself.

Just some ideas...





Here are some videos how complex mechanical can get. Completely mechanical torpedo's and computers.