Those first few words, the beginning of a new story or adventure needs to immerse the player into the world I am creating as quickly as possible. I like to write my ideas down in paragraphs, one for each individual story, if it grabs my attention, I feel I have a good one and flesh it out, seeding it with names of people and places, sometimes just locations. A valley in the east, mountains to the far south, nondescript places that could be anywhere and nowhere, places the player have been to or have never dreamt of.
These places lead to the people that live there, and their own lives and motivations that may, or may not, resonate with my players. I try to keep my worlds interesting and original, but tropes exist and are useful when your players need something recognisable to help them with their immersion.
The stories I tell rarely have a deep moralistic code, but do invite the players to interpret the tale according to their own ethical lexicon, inserting life lessons and points of view on the way. The players agency is unhindered and total freedom to explore situations is theirs. Now, I'm not saying there aren't things that occur in the stories that aren't terrible or sometimes shocking, but I do allow the players the freedom to look at all facets of the situations they come across and make their own judgments on what has occurred. I do however try to portray all the characters they come across in a believable way and give them as much authenticity as I can, to illustrate the repercussions of any one action, often cascading into a series of events sometimes unintentional.
Without trying to sound too pretentious, I try to distil the essence of what would be a protracted period of time, and give my players a condensed representation of what they might experience if the events they find themselves partaking in, had occurred in real life.
Sometimes intense emotions are sparked across the spectrum, from joy to regret, but in feeling these I feel that at least some elements of the human condition can be experienced and explored, even if the person you happen to be inhabiting, is perhaps not quite human...