Greetings from Japan. Most likely the first characteristic and maybe the most important trait a teacher must have is to care.
To care about the students...
To care about how to teach...
To care about what to teach...
To care about the teachings...
To care about the art...
To care about others...
To care is to put yourself second. The word sensei might mean one who comes first but that doesn't mean that you put yourself first. Sensei once quipped, "People don't realize that when they are served with things on a silver platter that they in turn must serve others as well."
Coincidentally caring is also the first characteristic of a student as well. Just substitute students for teachers and learn for teach. This is why the best students usually make the best teachers.
The relationship between a student and a teacher is symbiotic. The teacher thinks of the student while the student is thinking about the teacher. Each is concerned about the others burden.
This independence day weekend please enjoy your freedom. The freedom that someone else made possible for you.