Chris,
Thank you very much for your answers and encouragment.
I am more than happy to answer your questions.
My interim method consists of correct pronunciations, observation, and imitation or copying.
1. Correct Pronunciations
I could not differentiate differences between Enlgish L and R. To do so, I tried to pronounce any words including L and R such as world, religion etc and recorded my own pronunciations of those words repteadly for the adjustments like dancers dancing in front of mirrors while looking at how they are dancing. International phonetic Alphabets also helped me a lot.
This gave me better listening skills and confidence.
2. Observations
I recommend that my students go to language exchange event once a week to observe how native people speak and pronounce words including non-verbal expressions such their tone of voice, facial expressions, body posture.
I further recommend that they listen more than speak Japanese. To do so, I teach them simple interrogatives ( and interrogatives plus prepositions such as About what? In Japanese, interrogative plus particles). Our conversations or dialgoues are fundamentally composed of asking questions and answering them.
In this way, they can maintain a small dialogue with native speakers (For beginners, 10% speaking/90% listening is still rewarding.
Alternative for language exchange is watching a movie with this intent.
3. Imitation or copying
After observing, what I want them to do is copying. When I was a kid, I was trying to speak English like my favorite actor. In the context of language exchange, my students will bring what they heard in language exchange and discuss them with me. And then I encourage them to copy those expressions.
Seemingly, it is working rather than teaching grammars. Above anything else, my students are having fun with it!
If you can recommend anything for students to improve speaking skills, I woud like to know them from your side.