If I were to weigh in on this, I would say that the easiest way to proceed is to tell the parts that affect you most, the illumine, as Adam Smith puts it. If I'm writing a complaint to the West Haven Mayor's office, having gone down four feet on my bicycle into a sinkhole, and thereby getting an infection in one leg and two hours late for an appointment, I don't start talking about my appointment. I talk about the road bed giving way under me and sliding into a slurry of sand and sewer water. It's only then that I go back and say something like "I was under court order to meet with these people. It was stormy, but I still chose to go out. I took my bike because it was faster than the bus..." and so on, until I should break off and stop.
The same is true of fiction. To take "To Kill a Mockingbird" as an example, it would have been the easiest part to talk about how my father, Atticus, killed a rabid dog. It would have been very difficult to talk about how it started, which corresponds with how Harper Lee began, which is to tell you the outcome at the start, a device used by many lays and epics: this is the morte of King Arthur, this is how Great Beowulf slew the monster. Yet it's often hard to see when life went from "ordinary" to the intensified version known as "dramatic". For the writers of epics, it was, perhaps, simpler, because it was understood what "ordinary" was. For us, today, we have so many ways that life can be "normal" to people, so we must have a good deal of "establishing" material. So, I would say the most difficult place to start is the beginning.