I think there are a few qualities that are essential to be good teacher.
First he/she have to equip with a adequate professional. Secondly, a good teacher should be warmhearted, patient, loving. Good teacher not only teach students how to do exercises and acquire knowledge, but also shape their early idea. Thirdly, good communication is extremely impressive. Usually good teacher passively talk with their parents, which can effectively contribute to students' healthy growth and progress. A true story happened in China, an ordinary woman teacher, Zhang Guimei, lives in a small village of Yunnan Province. Her dream is to help girls go into the campus and build a girl school that is only for girls in poor family who can't afford the tuition. Her action was highly supported by local government. there are over 100 students got into first-class universities every year with the help of her. She patiently look after them in their life and strictly teacher them on study although she has a lot of disasters. Girls appreciated her pay for them and call her Mom Zhang.
Anyway, this is one of good teachers, I believe, for me, becoming a good teacher is hard, but action speaks louder than words.