After having taught thousands of class in the last 15 years I think I've finally figured out the two most important things needed in order to be a great yoga teacher, or what students should look for in a teacher, mentor, leader.
No, it is not how many advanced poses they can do or how they look in their yoga pants or whether or not they're vegan or vegetarian.
In my opinion, the 2 most important things one should look for in a teacher are that the teacher is a "good student" and has a self-practice.
What does it mean for a teacher to be a "good student"? When a good teacher takes a public class, she/he listens to the instructor, follows the sequence being taught and does not "do her/his own thing". I am not talking about modifying for injuries. I am talking about either embellishing every pose or doing different postures than are called out. To me, not only does this demonstrate a lack of respect for the instructor and the class, but it shows other students (possibly less knowledgeable ones) that they can and should do their own thing. It also shows an inability to learn from someone else, to be open to the possibility that their way is not the only way and that there are other instructors who might be able to teach them or show them a different, unique way of sequencing or cueing. In short, a lack of being open to new things.
The second important thing is a self or home practice. This is where a teacher should take creative liberties and try new things. See how various asanas and sequences affect their bodies and minds. This is where a good teacher can really learn the poses and the best way to teach how to progress or regress a posture or a sequence. This is how teachers grow and become better at their jobs.
To me these two things are the recipe for a yoga teacher that truly wants to educate and inspire his/her students. One I aim to be every time I step into the studio.