Principles of growth hacking
First and foremost, you should only focus on scaling growth when you're confident your product satisfies a true user need. Once you've achieved product-market fit, a simple framework can help guide your growth strategy:
Acquisition
What is the thing people are here to do?
How do you get them in the door quickly?
Activation
What is the "aha" moment or "must have" experience?
How do you get people to this point as fast as possible (i.e. in seconds)?
Engagement
How do you continue to deliver as much core product value as possible?
Virality
Notice that virality doesn't come into the picture until you've proven you can deliver a compelling benefit to users. Avoid gimmicks that drive sign-ups in the short-term but alienate users in the long-run. Finally, your growth strategy should be a function of your product. Some products don't necessarily have one big "aha" moment; instead, the user gradually discovers its value over time.
Tying your growth strategy to your product
Answering 3 key questions can help you decide how your growth strategy relates to your product. First, what's your product's "atomic unit"? This is the fundamental object that people are consuming and/or creating. Some examples:
Instagram - photo
Twitter - tweet
Tumblr - post
Dropbox - file
Codecademy - lesson
It's important to identify and hone in on one atomic unit. Juggling multiple often results in a disjointed and muddled product experience.
Second, what's your product's core benefit? Here's one way to go about figuring this out:
Identify your "must have" users - who are the people who would be very disappointed if they could no longer use your product?
Ask 20-30 of these users to explain the primary benefit they receive from the product. It’s ideal to ask these questions through an in-product survey, when users are in the mindset to answer them accurately.
Group then narrow down the responses to 3-4 benefit statements and ask people to choose their favorite.
Ask users why they chose that benefit.
Third, what's the KPI that predicts whether a sign-up will activate and become an engaged user?
For Facebook, it's getting an individual to 7 friends in 10 days.
For Dropbox, it's getting a new user to link a computer and add a file.
Every growth tactic you consider should be judged according to how well it aligns with your product's atomic unit, core benefit, and key user activation metric. Finally, once you set the growth metrics, it’s important to continuously question them – are these still the right metrics to focus on as your product evolves?
Optimizing sign-up flows
How do you evaluate different sign-up flows and decide where to allocate time and resources? The first step is understanding all of the various channels that are bringing new users to your product. Determine the conversion rate of each and prioritize based on the following 4 points:
It's easier to build on a strength than to improve a weakness.
Likewise, it's easier to get an active user to do more than to get an inactive user to do anything. LinkedIn, for instance, sends "Who's been viewing your profile" emails to active users of the site (20% CTR) rather than inactive members (5% CTR).
Desire - Friction = Conversion. It's a lot easier to reduce friction than to create desire.
Apply the 10% rule: Assuming you can increase the conversion rate of each channel by 10%, how many incremental users do you get from each flow?
After you find a flow that works, run A/B tests to optimize it. Having an A/B testing framework helps you make informed decisions, and it fosters a culture where data trumps opinions and where rapid iteration is encouraged. Keep in mind, however, that A/B testing will only get you to a local maximum, not a breakthrough change.