Memorize 5 new Kanjis every day.

To properly remember, you should:

• know how to write it with proper stroke order
  
• memorize the conjugated forms of the word
• master these elements of the word: the kanji, kana, meaning & conjugations
  

test out words you have previously remembered:

• take any word in any format (e.g. the kana version) then you should be able to recall the other elements (kanji,  meaning, & conjugations,).
• if you can successfully complete all 4 forms for the word every time, then you have properly mastered the word.

Grammar should be learned separately and in parallel.
To master basic grammar would take 10-15 hours.

Following this exercise, even if you are a totally new to the language, you should be able to tackle Japanese Language Proficiency Test level 4 (the lowest) in just 5 months.