Going viral by having your loyal customers becoming your brand ambassadors is a dream for every brand; this is what enabled my first venture Unyk to reach 20 million users in two years without doing any advertising (we later sold to Viadeo, #2 after LinkedIn, an adventure we shared with Wamda)

Do you have a shareable product? Your company needs to build a product that customers are proud to share. No one will share a poor quality product. 

Make it worth it to your potential brand ambassadors

If you already have an amazing product, it’s time to come up with an incentive to thank your brand ambassadors. Whatever incentive you use, it needs to be relevant and meaningful to your customers and their contacts. For example, in the case of internet retailers, credits or coupons are the most valuable incentives for users and the most efficient for the brand. Another type of incentive is directly related to the added value of the service. The best example here is Dropbox, which gives users extra space if they invite their friends to try out the service.

A/B testing is key to figuring out the best incentive for your customer. At my company Sociable Labs, our growth hackers are happy using Optimizely, a very simple and powerful A/B testing and optimization tool.

Sharing should be as simple as possible

Sharing user flows should be intuitive, easy, and frictionless. The key feature here should be to offer users easy ways to access their contacts or friends list from any social channel using official APIs, and then making friend selection an easy process. Also, A/B testing and optimizing the invitation messages your contacts’ friends receive make a huge impact on the viral loop. 

Aim your emails well

Email deliverability is the most critical factor to the success of invitation-based referral programs. Maintaining a clean email list and performing routine list hygiene is key to hitting the inbox. This best practice minimizes the risk of serious deliverability issues including blacklisting and global ISP blocking by hitting spam traps and having continuous, excessive bounce rates.

So, how can you keep your email lists clean? Get rid of hard bounces, and invalid and inactive email addresses. Also, take any support@, abuse@, postmaster@, hr@ addresses off your list. More than likely these emails have not opted into your list.

Get the word out

Finally, you need to let your customers know that you have a referral program in place. Newsletters, dedicated email campaigns, Facebook fan Pages, and order confirmations emails are some of the successful touch points our clients at Sociable Labs are using to promote their programs.   

General note: if you can’t measure it you can’t improve it! A robust analytics tool is the growth hacker's best friend. To optimize the virality, you need to define and measure all the viral loop key metrics in real time.