What vertical?
I have been generating leads for over 16 years. However, I mainly generate leads for financial type offers. Insurance, education, debt, loans, credit, mortgage, assistance, discount offers, homeowner offers, etc... They all have mass appeal and fresh / targeted daily data can be obtained for them...which is why I generate leads for those type of verticals.
I purchase or get rev-share 3rd party data, which is data that the users have given permission to receive messages from third parties. Then based on whatever the vertical is, I then send them a relevant PPL offer. So if I'm getting auto insurance data, I send then an auto insurance offer. If I'm getting education data, then I send an education offer, etc...
Additional theses types of offers are fairly easy to cross promote. Which is key to monetizing the data to it's fullest extent.
Outside of monetizing data, I would look at facebook ads. They have extensive targeting / retargeting capabilities.