I have this theory that the perfect blog post is eight sentences long. That's what I usually unsuccessfully aspire to when I start to write a post; four paragraphs, two sentences each, to cater to the diminished attention span of persons weaned on our modern communication age of texting, the Internet and Twitter.
It calls for a killer lede sentence. If by the third paragraph (fifth sentence) you're still setting up the story, go back and cut, cut cut.
I almost always fail. My interesting musings are usually still well underway when I arrive at the eight-sentence mark.
If you want to read killer first sentences in literature (aside from Moby Dick), read J.M. Coetzee. His Booker-Prize winning (1983) Life and Times of Michael K is a good place to start, a classic one-sentence table-setting.