I think the best way to answer that is I ask myself the question, "What if", and create a situation. "What if I had a family secret? What could it be?" That question resulted in the story of Eva as can be read in my "Twelves Strokes of Midnight".
Or, "What if that toy I had as a kid had some special powers?" - That resulted in "The Magic Carousel".
The tricky part comes down that sometimes the tales do not end the way I originally expect. "The Lady In White" was my attempt to do what I failed to do with "No More Goodbyes". Both of those stories took different twists to what I planned.