P.G. Wodehouse's advice on novel writing in his Paris Review interview has useful applications for journalism:
"Always get to the dialogue as soon as possible. I always feel the thing to go for is speed. Nothing puts the reader off more than a great slab of prose at the start."
The only thing that journalism has in common with classical epic, I tell my students, is that they both start in medias res. The Iliad doesn't start with the judgment of Paris or the abduction of Helen; as it begins, the Greeks have already been before the walls of Troy for a decade, their great champion Achilles is in a snit, and everything is going straight to hell.* We begin in the middle of the action, what is happening now.
A properly constructed story, especially aimed for the twitchy online reader, has two or three sentences, half a dozen at the most, to engage the reader's attention and establish a commitment to go forward. The way to do that is to go immediately for speed, to get to the dialogue, the action, the main point, filling in the back story later as you go along. Exposition can wait.
Thus: not Gregor Samsa had a troubled relationship with his father, and equivocal relationships with the rest of his family that left him feeling alienated, but Gregor Samsa woke up one morning to discover that he had been transformed into a large insect.
Starting out with some sort of prologue to the action is risky. Jane Austen got away with "it is a truth universally acknowledged," but I wouldn't advise you to give that a try.
And if you resort to what has become the most hackneyed of journalistic gambits, the anecdotal lead, you would be well advised to keep that anecdote as compact and succinct as you can, making sure that it connects graphically with the central point that is to come.
Once the story is launched, the key thing is to avoid losing momentum. It does you little good to skip some padded prologue if you then drift into longueurs or start resembling a term paper.
Wodehouse again: "I believe the only way a writer can keep himself up to the mark is by examining each story quite coldly ... and asking himself if it is all right as a story. I mean, once you go saying to yourself, 'This is a pretty weak plot as it stands, but I'm such a hell of a writer that my magic touch will make it OK,' you're sunk."
Cast a cold eye. Keep yourself up to the mark.