"There's incredible power in it" - Stephen King on Opening Lines
I tackled first lines right away for the same reason horror author Stephen King spends weeks and months and years on his: through their voice, they beckon the reader to stop, stay a while, and listen.
I highly recommend reading Joe Fassler's interview with Stephen King from The Atlantic's By Heart series: Why Stephen King Spends 'Months and Even Years' Writing Opening Sentences. A discussion of his favorite literary passages turned into an examination of the influence and importance of first lines. Through examples of his personal favorites and his own opening lines, King explains how these first words hooked him and why he bases the life or death of his ideas on first paragraphs. I think the final paragraph summarizes it best:
A book won't stand or fall on the very first line of prose -- the story has got to be there, and that's the real work. And yet a really good first line can do so much to establish that crucial sense of voice -- it's the first thing that acquaints you, that makes you eager, that starts to enlist you for the long haul. So there's incredible power in it, when you say, come in here. You want to know about this. And someone begins to listen.
Practice the power of opening lines. Take the 30 Day First Lines Challenge.