Hi Emma, A couple ways: every staff meeting started with kudos and Flubbos - what went well, what didn't. Often if someone said "well, I tried this...and it..." then another staff member would say, "Oh, I know how to fix that". I would share about my tries and fails as well. So the routine was that we share our experiences, learn from each other; Modeling growth from failure is a huge part of making it safe for teachers to try new things.
Another was an absolute commitment from me that no one could fail bad enough that we couldn't pick it up, clean it up or put it back together. No one was held accountable (through evaluation or other punitive measures) for trying and failing.
Another way was to find a way to say "yes" to almost everything. I shifted some funds to support teachers who wanted to time to develop something new. Yes, was the go-to answer, no, was the outlier.
We keep these at the forefront for staff and in our classrooms. I think we can talk structure, spaces and time, but if we don't deal with the human element of fear (around failure, letting someone down, consequences, etc.) then innovation will be stagnant. When the fear is gone, then innovation and creativity can blossom.