There are many different ways to start a story. The first rule of thumb is to always open with a hook. Draw the reader into the story. To think of this in visual terms, when a reader opens a book and reads the first line you want to reach out and grab them by the throat and suck them into the work. Right. How do you do this?
Start in the middle of something. Action or dialog are great starters. But warning, don't use action or dialog that does not have a purpose or it will only confuse the reader. Don't be concerned if twenty pages into your story, you find your opening. This is also normal. Yes, it's hard to cut those twenty pages. Do it anyway. Think of those pages, not as a waste or loss of time and effort, but as your mind's way of working toward the perfect opening. Everything you write has purpose-just not necessarily for the reader.
But, you say, some people can open a book with sweeping descriptions of vistas and sunrises. Yes, some people can. This is rare in today's market and not the norm.
Why are beginnings on my mind? When I first started writing I was content to write one opening and revise the scene to polish. But in the case of my last two manuscripts, I've written two or three different scenes as openings... and it's been fun. What I've got is a good, better, best scenario. The goal? To reach out and grab the reader by the throat and don't let them put it down until they reach the end. Then, like a roller coaster, leave them wanted to read it again...