In my last column, I said you would be able to abandon the "shotgun" approach to marketing. Database marketing allows you to do that by zeroing in on your most highly qualified prospects-those people most likely to be interested in your seminars or conferences. It acknowledges that not all of the prospects in your database are equally likely to become customers. Repeat customers have a measurable, long-term, ongoing value. Generally, we can readily divide our prospect population into three broad categories: best prospects, second-best prospects, and least-best prospects. These categories vary significantly in the degree of bang for your promotional buck. Consequently you should consider a differentiated marketing strategy which factors in the variability of prospect response.