From Conor Neill’s article When you lead there is no such thing as a trivial act:
What do you know that is “wrong” but tolerate? What behaviours annoy you, but you don’t address them? If somebody arrives 4 minutes late to a meeting, are they allowed to attend? If somebody sends the report an hour later than agreed, are they sanctioned?
If you allow bad behaviour this is who you are. Words are cheap. What you allow is real.
What are your intolerables? What are the behaviours that you absolutely will not sanction? If you are not clear on this list, then you will allow bad behaviours to creep into your culture.