Have you seen Foursquare for Businesses? The easiest things to do first is to offer deals on twitter for foursquare checkins. Another thing you can do is if you have retail space to make sure you get a sticker/cling for each store front.
Here is a quick list (courtesy of good friend Cheryl Harrison that I have expanded on) of things you can do to promote foursquare checkins:
+ Loyalty card. “Free x for every x number of checkins.” (printing, business cards, brochures, etc.) Daily, Weekly, Monthly Be unique and get people’s attention by offering more than 10% or 20% for a “one time” offer. Brand loyalty comes when the customer service experience turns into word of mouth marketing not spending more money on traditional marketing techniques. Make them feel special and unique. Read more