DanG: Having served a sentence as an editor ... I can assure you that most often the first paragraph of anything written by most people can safely be eliminated. It takes practice to hit the ground running. The screwiest letter I ever got as an editor was 6 pages long. I made the mistake of writing the guy back (I was new). I asked him to pare it down a bit, as he did have something worthy of saying. He replied with a 12 page letter, one that spent most of the time calling me an idiot for rejecting the 6 page letter. Around the office we called those long letters "When the Dinosaurs..." letters; most of them framed their arguments by starting with ancient history.
DFO: The key to writing a good letter is the same as writing an editorial -- figure out what you want to say and a point or two you want to highlight. Then, zero in on that basic outline. Stay away from rabbit trails. Indeed, a lead paragraph by an unskilled writer often can be eliminated. The same can be said for the last graf or two -- even those written by a skilled writer. Often, when I stumped for an ending to an editorial or column, I check out the preceding graf and see that my thought actually ended there. DanG's comment reminds me of that old saying: "I didn't have time to write well; so, I wrote long."