I would recommend everyone involved in teaching mathematics to read the book “How to teach mathematics” by Steven G. Krantz. It contains lots of practical advice about how to improve your teaching.
After reading the book by Krantz, I started to pay more attention to “small details” which may have a great psychological effect in teaching, for example, a very clean blackboard before starting each lecture.
A review of the book (2nd edition, 1999) can be found here:
http://www.maa.org/reviews/howteach.html
One can find the book in many online bookshops (and can also download the book from the internet if one can’t afford to spend 20 dollars on it)
anhtamct on 
shahkhi on 
Ngo on 
TaiTran
Yes, I would like to recommend that book too, it is widely used in some maths departments in US universities
In face, every first year grad -student has to take it before they are allowed to teach their first courses
It is extremely useful and we have learned a lot from it.
I have bought a copy of the book as you recommended. It’s so useful. And hopefully, my TA evaluation this quarter will be higher thanks to what I am learning from the book (the evaluation was not very high in the last two quarters, mainly because of my strong Vietnamese accent).
Thanks Prof. Dzung so much for that. We are grateful for your uncountable contribution for Vietnam maths. I have a small suggestion for you: if possible, could you please create a new category in your homepage, say, “links of possible scholarship” to help Vietnamese students. I think, with your worldwide relationships and reputation, it would be lovely chances for young generations in Vietnam. Thanks.