Why are you so scared?
Because I just saw the whole of my future life, and it didn't take very long.
~ Terry Pratchett (April 28, 1948 - )
Above all, a query letter is a sales pitch and it is the single most important page an unpublished writer will ever write. It's the first impression and will either open the door or close it. It's that important, so don't mess it up. Mine took 17 drafts and two weeks to write.
~ Nicholas Sparks (December 31, 1965 - )