People have asked me how do I pick a location and/or time period for a new story? Well, that's the fun part! I do my best thinking lying in bed just before falling asleep. Often my head is so full of ideas and thoughts I never fall asleep! Basically, I think of a time and place I would have liked to live, such as Medieval Times in England. Or back in biblical times. The characters come easily once I know where and when I'd like to write about because the characters are born from the era. If I'm writing about a war, it stands to reason one of my main characters will a soldier. I've written two novels with military heroes, My Life, My Heart and On Angels' Wings.
Then I keep a file with new ideas and a working synopsis of each idea for future projects. If I'm in bed when I devise a plot, I get up and write it down so as not to forget it by the next morning. Many ideas for novels have come to me that way.
Picking a location is half the fun of writing. It allows me to live vicariously through my characters and my plots. It's like living a multitude of life times! The writer's life is great!