Amplify the positive outliers

The most efficient way to get the behavior you're looking for is to find positive deviants and give them a platform, a microphone and public praise.

The tribe is hyper-aware of what's being celebrated, and when you celebrate those that are moving in the right direction, you create a powerful push in that direction. It's tempting to spend your time extinguishing bad behaviors, but in fact, spreading the word about the superstars is far more likely to change the culture of your market.