Just like issuing a dare, offering a challenge motivates people to step up and do things they might not do otherwise; like pour a bucket of ice water over their head. The challenge can include some sort of giveaway or reward for showing up logging in or commenting on posts for a certain number of days or some other type of challenge, but should certainly require an email address to enter.
Word of mouth communications and peer-to-peer dialogue often have a greater effect on customers, since they are not sent directly from the company and are therefore not planned. Customers are more likely to trust other customers’ experiences. Examples can be that social media users share food products and meal experiences highlighting certain brands and franchises. This was noted in a study on Instagram, where researchers observed that adolescent Instagram users' posted images of food-related experiences within their social networks, providing free advertising for the products.
Because users have different operating systems, web browsers and computer hardware (including mobile devices and different screen sizes), online ads may appear to users differently from how the advertiser intended, or the ads may not display properly at all. A 2012 comScore study revealed that, on average, 31% of ads were not "in-view" when rendered, meaning they never had an opportunity to be seen. Rich media ads create even greater compatibility problems, as some developers may use competing (and exclusive) software to render the ads (see e.g. Comparison of HTML 5 and Flash).
When you meet people face to face for any reason, ask for their business card. Offer yours. Set a glass bowl on the counter in your store or the reception desk in your office, and ask visitors to drop their cards in it. Offer some incentive to do so — a free product or service, gift card, etc. Use your own business cards to further drum up emails; add an offer on the back of your card that encourages people to sign up to receive your emails.