Make an assessment of your finances and timetable and ask yourself how much money and time you are going to devote to learning Japanese. Also consider the reasons that you intend to learn the language.
Buy a book-type English-Japanese/Japanese-English dictionary. Use it ONLY when you cannot understand words from context.
Buy yourself a Japanese course on audio CD. Listen to it even just an hour a day, especially while you are on your way to work. Install it in your portable music player and listen to it during break time.
Consider taking up formal studies in a Japanese college, an intensive crash course program or night school.
Buy any book, comic book or game in Japanese that you will find to be exciting.
Use flashcards for practice. Use flashcards with vocabulary and simple phrases or those with Japanese characters. You may also write your own lessons on blank 3-inch-by-5-inch flashcards.
Join one or two conversation groups that regularly meet and use Japanese. Find one in your area by trying to contact a public library by email or phone. Train your ears to pick out what is being said and repeat what was spoken. Never hesitate to ask questions.
Make Japanese friends with whom you can regularly speak. Go traveling and sightseeing. Learning the language and having fun at the same time is like being able to hit two birds with one stone.
Go on a short vacation in Japan. Review the itinerary and visit historical places and ask questions in Japanese.
Look for an opportunity to live in Japan. The real test of your Japanese-language skills is staying in the country for a relatively long time and being able to live.
Watch some videos or DVDs of movies with Japanese language but English subtitles that you can turn on and off as you wish. Watching Japanese movies without English subtitles could be very difficult for a beginner in the language.