In this stage, first time visitors becomes ‘light’ users. 
You can reassure and trigger them. 
Create nice simple interactions while visitors don't have to register themselves.

Why not trying some nice games on social media, like KLM did? 

 

 

 

 

 

 

 

 

Or try one-click-aways' for getting nice rewards

 

 

 

 

 

 

 

Or create votes in a hot-or-not-machine 

 

 

 

 

 

 

 

Does that make sense?