I was born in China and raised in Japan. I have experience of teaching Japanese in Singapore for 3 years. (~JLPT1).
As I speak Japanese, English, and Chinese, I understand how difficult learning a foreign language is. The most important thing in learning the language is to listen and speak a lot with native speakers.
For advanced learners who are already able to speak Japanese but not so fluent, I basically use Japanese in the class to expand your vocabulary and range of expression.