Master the Majority of Common Words
Having completed the Vocab Mastery course in Phase 2, along with several grammar courses, your vocabulary will be fairly awesome at this point in your studies.
That said, there is a lot left to learn.
To further improve your Japanese vocabulary, we recommend going through our 300+ random-topic NDLs. These lessons cover a variety of topics, so they tend to be a bit more enjoyable than grammar-centric JLPT lessons.
In reading them — and doing the flashcards and audio loops that accompany them — you'll also pick up over 4,000 new Japanese sentences, which will be a huge boost to your Japanese vocabulary.
You can get the flashcards and loops on the NDL Resources pages. The lessons you can find here: