Some Options:

i) Going to classes that are private taught such as at community colleges, schools, private institutes and tutors.
ii) Audio Books
iii) Workbooks and Phrasebooks
iv) Knowing a Native Japanese speaker would be helpful, or going to language meet-ups (if there are any) in your area to exchange languages.
v) Online & computer resources such as Pen Friends, online language exchange, games, flash cards etc

Classes I find will be the most productive example, especially if it's with a Native speaker. Generally mixing everything together there would be the most ideal but even getting a Hold of a good Audio Book, workbook & phrasebook and using online resources would be ok.