Every writer knows how important a strong, engaging, punch ‘em in the gut opening is to selling a story.
It’s the antithesis to the way we teach schoolchildren to write letters, beginning with “dear so-and-so” and proceeding with “I am writing to you...”
The first paragraph is a rude thing. With it, we must break ingrained habits of polite address, which build methodically and leisurely to the point of why we are writing in the first place. None of that pitter-patter to the entrance, folks.
But I find the first paragraph serves not only to engage a reader, but to set me, the writer, on the right course. It is a reminder of who, (the voice, i.e. the personality of the narration) the why, (why is writing the whole thing worth my while) the what, (the theme is embedded right there) the where, (at least in terms of how it's emotionally situated if not physically as well) and the when.
If, along the winding way of first drafting, I find myself unsure of any of the above^, I re-read and reorient with the help of that first paragraph. In the event that it doesn’t serve to correct my writerly meandering, it’s a failure.
It’s not only for the reader or the marketing department. Great first paragraphs are the writer’s lighthouse to get back home.