Some may argue that asking for opt-in results in a smaller contact list since customers have to perform this extra step. However, not asking for permission before sending puts you at risk of being marked as spam or worse, being blacklisted by an ISP – and obviously at risk of fines, since May 25th. Just one abuse complaint can lead to having both your Domain name and IP addresses blacklisted.
I always pause and laugh when I see a CTA with a small, “No thanks, I don’t want to lose weight,” button underneath a prominent “Yes, sign me up!” link. It reminds me there’s a person behind the button, and, while it’s meant to be a joke, it also incentivizes me to hesitate before clicking “no, thanks”. It’s easy to click “no” when the CTA is “sign up for more emails!”, but it’s a little harder to say no to losing weight or getting richer.
Appropriately ending our discussion of opt-in forms is the exit-intent popup. As the name implies, these pop-ups show up when users display a behavior indicating their intent to leave the page. Triggers for exit-intents can be rapid mouse movement toward the top right of the screen (where the close button typically is), clicking on off-page links, set on a timer, or activated on scrolling.

Some ad platforms will ask more of your landing pages than others, when running ads. For example, AdWords is much stricter, when compared to Facebook. AdWords typically requires that you do not have a ‘thin,’ site that is designed solely to collect leads.  Because of this it might be a good idea to focus on using Facebook or Twitter, to begin with.