First,to be a good teacher,you have to restrict yourself; to be a good English teacher,one has to master English and Chinese both very well!Those things are essential to be a teacher,either English,Chinese or Maths,any kind!
Second,to be a good English teacher,one has to master the skills of teaching.The teacher's role is not only a teacher pushing knowledge to the children,but also acts as a guider,an organizer,a role-player,etc.Anyway,responsibility is a complicated word,which involves many meanings,especially when it comes to teaching!
Third,be the friend of the students.Enlarge their knowledge is one thing,but another important role of the teacher is to communicate with them,to be close to their soul!
Anyway,if your like teaching,you can be a good teacher!