I've always preached that a good sales letter should choose the right words to get someone to act. This hit home last week, in my own family life. My wife spent an entire day tearing up our house looking for a book that Rudy, my three-year-old son, had thrown somewhere. My wife couldn't find it anywhere. And of course Rudy wasn't any help. We'd asked him to "look for the book". He'd look ... straight ahead and in one or two places and that was it.
This went on all day. No book. Plenty of frustration. My wife doesn't give up, though. Six hours into the search for this $1.95 book, she was about to ask Rudy once more (this was about the 250th time now) to "look for the book". But she was tired. She just sighed and said, "Rudy, find the book" instead of "look for it". Took him about three minutes of searching but he "found" the book. Seems my wife's intent was there in telling him to "look" for the book, but he couldn't understand her until she rephrased the "sales pitch" so he knew what she wanted him to do.
The same thing works in your sales letter, advertising piece, and promotional material. You know the message you want to get across. You know your goals. But your prospect is not you, and doesn't know how you think. You've got to carefully choose your words to get your prospects to react the way you want them to ... and increase your overall sales.