Any journalist knows that if you don't hook the reader with your first line you've lost them. This is true of all forms of writing. Your first line needs to do a lot of work and there is no better example than John Steinbeck's opening paragraph to Cannery Row. It is a beautiful piece of art worthy of hanging in the Louvre or any other fine art gallery.
“Cannery Row in Monterey in California is a poem, a stink, a grating noise, a quality of light, a tone, a habit, a nostalgia, a dream. Cannery Row is the gathered and scattered, tin and iron and rust and splintered wood, chipped pavement and weedy lots and junk heaps, sardine canneries of corrugated iron, honky tonks, restaurants and whore houses, and little crowded groceries, and laboratories and flophouses. Its inhabitant are, as the man once said, “whores, pimps, gambler and sons of bitches,” by which he meant Everybody. Had the man looked through another peephole he might have said, “Saints and angels and martyrs and holymen” and he would have meant the same thing.”
As a learning exercise, go out and pick a few random novels or narrative nonfiction books from the bookshelf and read the first paragraph. Which one compels and impels you to continue reading in the same way that Steinbeck's opener does? Which one makes the biggest, boldest promise to you the reader?
This is why the opening line and/or paragraph is so important. People want a great story to read and the opening to your story must make a great big promise to the reader. It must promise that you will not waste their time with wordy, boring, irrelevant self-indulgent crap. Steinbeck makes a great big promise.
Obviously, the trick here is in the execution. Some sit and write and rewrite until they've beaten the opening too death then go to bed and as they lay on the verge of butterfly dreams, the just-right idea hits. This is why you need paper and pencil nearby at all times.
Another trick I learned from an exceptionally talented former reporter for The Baltimore Sun is a bit faster and funner. He told me that as I stare at the blank page and prepare to write that I should clear my mind, close my eyes and say, "You won't fuckin' believe this but," and write the first sentence that comes to mind.
This may not be the one you keep, but it will do something that I call Harvest a Blink. This comes from Malcolm Gladwell's book titled Blink in which he asserts that more often than not, the first thought that comes bubbling up from the subconscious is the best thought, or at least a good one.
By harvesting your blinks, you are reaching past the front of your mind where you have all of your worries, anxieties, and to dos clogging up your thoughts to gain access to the rich reservoir that is your subconscious mind.