My school has developed an in-house design consultancy made up of teacher leaders who meet every other week to design professional experiences for our colleagues. More than any single initiative we took on this year, our development of our group's norms has been essential to promoting an innovative culture. These norms were created by the group over time, empowering everyone to be involved in both their creation and enforcement. The shared responsibility that these norms embody has made everyone consistently both accountable to and responsible for each other.
First and foremost among these norms is the creation of "challenge slams," which are fifteen minute chunks at the beginning of every meeting in which one member brings a challenge s/he is facing in her practice. The group then spends fifteen minutes brainstorming ways to help that teacher through the challenge. This is led by a different teacher each time, so that we all share the responsibility of both helping others and organizing the sessions.
Maintaining a culture is a sisyphean task that requires constant vigilance. Having an anchor like these norms has made it significantly easier to do so.