Screen.
A "soft" offer is one that solicits a lot of response, some of it sincere and some of it shallow. Soft offers include free trials without commitment or obligation. A "hard" offer will disinterest those only marginally intrigued by what you are marketing and instead will identify those with urgent, core needs.

Sort.
The degree to which you qualify respondents depends. Factors include the relative scarcity of prospects, the cost of conversions and the marginal profitability of a new customer. Fewer respondents may be more profitable if the sales process is costly. More may be attractive if marginal profits are large.

Progress.
Use progressively finer mesh screens to separate those you will continue to solicit from those you will ignore.