You need to get to know your target group before you do anything, this is valuable data you can use to support your actions.
ANALYSE THE DATA
When you have gathered information about your target group, go through each one of them, and find similarities, the issue that occurs the most, solve it!
BUILD AN INFO PRODUCT
Based on all the data, you now know what issue to solve. Solve this with an info product you give away for free in return for the visitors e-mail.