What are the key metrics for your service? Think about all the metrics that will help you determine whether or not your MVP is delivered.
Write all of 1-10 key metrics, each on their own line.
These key metrics are the main metrics you need to measure and optimize for your business to grow. These metrics will also tell you whether or not your MVP works.
Twitter found out that when a new user follows at least 30 users on their first visit, then the user is a lot more likely to become a permanent user. So, one of twitter's main key metrics is actually the number of followers/new user. They make it as easy as possible for you to follow 30 users upon your first login.
# of tweets
# of followers/user
# of referral signups
# of photos uploaded