Watch Japanese television shows and movies to get used to hearing the language at a normal speed. Rent Japanese movies and television series on DVD from a video rental service with a good foreign language section. Learn colloquial dialogue and idiom by watching Japanese movies that you enjoy as many times as you can.
Read Japanese-language newspapers, magazines and books regularly. Build your vocabulary by looking up words that you don't understand and writing down their definitions to help you remember them.
Keep a journal or blog in Japanese. Make audio or video recordings yourself reading your journal or blog entries to improve your pronunciation.
Practice conversational Japanese regularly with a language tutor. Find a native or fluent Japanese-language speaker through the foreign-language department at an area university, or through websites such as Craigslist or Meetup. Meet with your tutor weekly at a coffee shop or another location that's convenient to both of you for conversation. Ask your tutor for feedback about your pronunciation, and practice words you have trouble saying until you correct them.