You're bound to attract a large gamut of people. From dabblers, to drivens, to the people in between.
Ultimately, at the end of every meeting, ask yourself, and the group, who contributed the most to the meeting? Also, if you had to rate everyone in the group as either a positive energy giver, or a negative energy sucker - meaning someone who contributed, or someone who anti-contributed, what would you rate everyone?
You want a group of momentum-increasing, positive-energy-giving, passionate dynamos whose purpose aligns with your own. People you don't drag to meetings - people who arrive with materials they're itching to demonstrate or questions they've been dying to ask.
Make a team based on character, emotion, passion, and drive. Knowledge comes from those traits. You could have the smartest person in the world on your team, but if they use their talents for negativity, all those talents work in the opposite direction.
If you are a leader, or a member of a group, you may want to start keeping track of simple -1, 0, +1 ratings of people at the end of each meeting.
In the beginning, people's ratings will fluctuate wildly. -1 because they're scared or defensive of their former lives. 0, because they're insecure about their knowledge or life experience, and +1 because of that initial spike of passion.
After about a month, check in with your ratings, and start making judgement calls. Ultimately, the investment group is an entity all on its own. Its up to each one of its members (and especially its leader) to keep that entity not only alive, but flourishing.
Sensei Ono, Shinka Martial Arts
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