Listen to Japanese talk radio/podcasts/ audiobooks/audio clips
Utilise your spare time whether it will be waiting in a queue, walking your dog, washing your car etc. Use all such time to listen to the podcast, audio clips, basically any audio resource you can lay your hand on, to be able to gather more vocabulary and correct accent.
Music plays an immensely important part in our life.
It is so evident from the fact that Alzheimer patients who forget the names of their loved ones, situations, have been known to recollect song lyrics and tunes! Song lyrics can also help you to improve your vocabulary. Also, singers tend to pronounce the words more clearly than people. By memorizing songs, you will learn the pronunciation better!
Seek other reliable audio resources online that can help you learn.
A learner who wishes to learn to Japanese should listen to Japanese news as it is spoken more formally and clearly. They are also a great way to add new vocabulary words to learn!
Use SRS to excel
I could suggest proven apps such as Anki and Memrise where you can learn through existing decks or create your own!
Try Mnemonics to improve your learning
Mnemonics is another popular method to further your learning by memorizing the existing Japanese words, phrases into something known and common in your own native language.
Practice, practice, practice! In the end, it is the only practice that is going to help you learn the language.
Try the Pomodoro technique!
Spending 45 minutes at spaced intervals, 3 times a day, everyday, rather than spending long hours at a stretch on the weekends.
Find a conversation partner to converse and seek feedback from to improve your learning. Look for conversation partners around you, in your neighbourhood, any community near you; if you don’t find one I suggest going online on Conversationpartner, Tandem, Languagepartner, Italku, Hello Talk etc. Review again and again.
After you are confident about your pronunciations and the accent, I recommend you talk aloud and record yourself. Then hear yourself again and correct your mistakes, to re-record yourself. You may continue doing this until you get the right pronunciations in one recording.
