Facebook Like Box
A great way to stay in touch with first time visitors is by getting them to like your Facebook page. It’s the most popular social media channel out there and is far easier for a user to opt into than a newsletter. You can easily add a like box to your website by visiting the Facebook page to generate it.
Just don’t forget to actually engage your new audience on Facebook (but don’t spam them or you’ll lose them as quickly as they came in).