If the job of the headline is to get readers to read the copy, then you might say the job of the first sentence is to get readers to read the second sentence.
That may seem obvious, but it can easily be overlooked — whether a journalist sweating his lead (or lede, if you prefer), or a copywriter overreaching with the opening sentence of body copy. Sometimes we writers try too hard, as if we want to be Shakespeare or Hemingway.
Larry McMurtry offered some good first-sentence advice in one of his novels. (I think it was in Some Can Whistle.)
“You expect far too much from a first sentence,” McMurtry wrote.
“Think of it as analogous to a good country breakfast: what we want is something simple, but nourishing to the imagination. Hold the philosophy, hold the adjectives, just give us a plain subject and verb and perhaps a wholesome, nonfattening adverb or two.”
Something simple, but nourishing to the imagination. I like that. That will surely keep readers reading.