You need a business strategy to go with your letter and your list. In direct mail, strategy means numbers and projections. The only way to come up with effective direct mailings over the long haul is to test your offers, your lists, and your projections in a series of mailings. In your initial mailings you will rarely know precisely what to expect.
Many people think that with a new client the first order is the hardest to get.
In direct mail, that's not quite true. Direct mail expert and professional list broker Ed Burnett argues in his Complete Direct Mail List Handbook that the hardest part of direct mail is converting a one-time customer into a regular. That's why many catalogue companies will create special orders targeted specifically at their one-time buyers to persuade them to make a second order. Simply expressing price in different ways can dramatically affect your orders. This is especially true for promotional offers.