I think a   good teacher must have insight into the difficulties a student will encounter

when expressing themsvles.

  A good teacher will first and foremost,  remove fear and tension from the student.

  A   good teacher  has a clear comprehension of the specific processes and stages involved

with the acquisition of language.  For example,  the stages can be identified as the following:

(a) Pronunciation    (b)  Sentence construction in the form of Subject/Predicate  or Noun/Verb

(c) Abstract Concepts and Transcendental Relations.  (d) Distinctons as to basic knowledge disciplines such as Science,  Law, Philosophy,  Theology,  History,  Art  etc.

Why do you want to become a teacher?

@tu anh i totally agree with you
in addition i think he should be also a motivator.

You have to have a wide knowledge, good skills, more and more patience, understanding and a bit humorousness.