Starts with picking an important mission: someone you care about deeply with an unmet need that is real, and that is very important to them and to you. An unmet need so big and important that you can't imagine not spending your life solving this problem.
Then build you team of folks similarly "all in" on the unmet need.
Build a culture where everyone on the team is aligned to solve the problem... and cares about each other.
The best team builders solve very different unmet needs, but have similar models on how to build winning teams to solve those problems:
Lou Holtz, famous Notre Dame football coach, said if everyone on the team can answer yes to three questions, you'll have a winning team:
1 can I trust you?
2 do you care about me?
3 are you committed to excellence?
Google in Project Aristotle came up with two questions that predict a winning team:
1 does everyone get roughly equal airtime in meetings?
2 do you feel psychologically safe on the team?
Jeff Bezos at Amazon famously used the two pizza rule to build great teams: design your teams to be small enough to truly know each other and care about each other, so they feel belonging with/to each other and outperform. And use the PR/FAQ to help the team envision upfront how much better the customer's life would be the day a solution was launched.
Jesus picked a two pizza team too, and focused his team of 12 disciples on praying, serving, and socializing together to build true belonging with each other, Then he taught them how to love each other better with his Catholic Virtue Ethics culture model of thinking of others first vs yourself. Then sent them off two by two to go build more 12+1 teams yielding a viral multiplier that has led to 100m of these teams today.
All very similar key themes: 1. do you deeply love your customer who has the unmet need that you are solving, 2. do you love each other on the team so you work together effectively to solve that need. Layer in the winning metrics so you know the "how" to point yourselves at iterating to nail the solution.
Tools like @Brett Hellman built with http://matterapp.com can help you on 1 and 2. Platform's analytics team can help you track the iterations with the winning metrics. 58k people are standing by to help you in the Platform community.
Simple right? 8-)