You can use the Affiliates Manager plugin with iThemes Exchange plugin so that referral commission is given to affiliates that send you visitors to your store.
The affiliate manager plugin has built in integration with the Exchange plugin so you don’t need to do anything extra.
Keep these two plugins active on your WordPress site and do the basic setup configuration. After that, you will be ready to start accepting affiliate registration on you site.
Your affiliates will be able to send traffic to your website and get rewarded for it when a customer (referred by the affiliate) purchase a product from the store.