Groupon has been one of my most effective marketing tools—my first deal alone sold 10,500 units with an estimated 60-65% customer retention. In the past three years, we have experienced an 18% overall increase in new business, much of which I attribute to using Groupon. Key to success with Groupon is managing and preparing staff thoroughly for the increase in customers, along with limiting the number of deals offered and carefully managing what is offered.