Assuming you have attended a quality Japanese language course..here are our Top 7 TIps to Ace JLPT Exams.
1. Brush up on Kanjis, compound words like だいがくetc
2. Read Renshuu A of every chapter of Minna no Nihongo. This will be a brush up of grammar patterns.
3. Save audio files of vocabulary in phone and keep listening while walking /traveling etc (be careful while driving!).
4. There is plenty of Choukai practice on Youtube..along with script . Practice those.
5. Practice Dokkai passages. Reading speed and Kanji recognition should be good to comprehend and solve the passages within time.
6. Memorise vocabulary and grammar patterns with particles.
7. Two mock exams available on the official jlpt website. Time them and take the tests