Refer a Friend or Repeat Guest Promo

Then, I was trying to think about something fun and different, so the first thing I came up with the "Refer a friend" and/or "Repeat Buyer" program, where either could save some money when purchasing my items. I designed some cards as well as some labels, and also have been emailing the card to those who have purchased items lately from my shop. I haven't had anyone use the promo yet, but it has only been about a week, and I'd like to test it to see if it will work, or if people even care to use it.