A Sales Funnel Report can be run to compare the actual situation at each stage with your sales budget or plan. The funnel can indicate if any specific level is acting as a bottleneck and needs more effort directed to it, or if resource can be taken from one level and deployed at another. It can indicate whether or not a sales budget can be met, or if more leads have to be added to the top of the funnel. It can also indicate at what point leads drop out of the system, and what action is required to maintain a steady flow.
In order to build a sales funnel, you need prospects to pour into the top. Your objective is to end up at the bottom of the funnel with people who have been qualified at various stages in your funnel to become responsive buyers of your products. The first stage is to get email address by means of a squeeze page. Everybody who fills in the opt-in form becomes a prospect and falls into the funnel. As they receive and read your newsletters, they continue to filter slowly down your funnel, and then you offer them a product.
It need not be an expensive product: a $20 book will be enough to start with, and everybody who buys it establishes themselves as a customer and falls further down the funnel. Many will not make the purchase and your funnel will become narrower, but you can calculate at each stage how much narrower it becomes. As you offer more expensive products, your funnel will become narrower and narrower, till at the end you have customers who are very responsive to your offers, and it is them from whom you will make the bulk of your money.