3. What's The Most Vital Copywriting "Secret" You Will Ever Find?

For boring sales letters, doing just this one secret thing, was often like throwing the switch on an extra fuel tank. And for new sales letters, applying this insight first made my whole marketing effort fall into place.

While it is true that copy will always matter a great deal, I also discovered that 9 times out of 10 there was an even easier secret way to double and triple sales results, that didn't involve writing much new copy at all, nor was lining up new and expensive lists of customers to mail to. So, once again, what is it?