I think a big part of teaching a language that often gets neglected is why people fail or don't achieve what they were hoping for or even give up.
A big mistake in trying to learn a new language, is not understanding the fundamentals and grammar of your own language. People assume if you can speak a language it's the same as understanding it. If I'm trying to say a sentence in another language if I don't even understand how that sentence works in my own language , how can I expect to say that sentence in another language? Conjugate this! IS this the passive form? What's the present perfect? While I'm not suggesting for learners to become scholars in their own language you need to understand basic grammatical language!
2. My way of studying or the high way- I've studied with various Japanese students and teachers as well as English. While natives can offer unparalleled expertise in he or shes language don't assume that the way they teach you is the only way. Whilst Japan do have a more regulated form of learning language than the west. IF you were not born in Japan that style of learning just might not work for you! Incorporate if you can ! But develop it to suit your needs!
3. Proactive learners are the fastest learners: IF you're not getting better you're getting worse! Sounds harsh but it has some truth. Television, books, comics, lessons, groups ,pen pals, meet up..with the internet there really is no reason you can't be learning Japanese.
(benkyou sureba benkyou suru hodo jyouzu ni narimasu).
The more you study, the better you get.