Happy customers are the best possible advertisement for your business. Unsurprisingly, one of the easiest ways to earn happy customers is by giving away free stuff.

Companies like Dropbox and Uber regularly give away free file storage and journey credits, creating evangelical customers in the process. These free gifts are offered as referral incentives: in exchange for an awesome freebie, your users simply need to invite a couple of their friends to your service. As well as creating a feel-good dynamic between business and users, you can use referrals as a serious source of growth.