Learning a new language can be difficult, Japanese especially so. However the more of a grasp you have on the language, the easier your life in Japan will become. Sounds like common sense right? Surprisingly this isn't the case for everyone who comes to live here, and with good reason. There are hundreds of methods and resources available that are supposed to help you, some can be rather expensive as well. Often it comes down to a lack of direction or not knowing what to do next. Especially if you take the self study methods. Lets take a look at some of the resources available to help you continue your language study after you move to Japan.
Language schools
By far the most expensive option is to enroll in an intensive Japanese language school. There are many throughout Japan and could be perfect for those who need that structure and push which they provide. Each school will have a variety of programs to choose from to fit your needs. Some programs are more of a crash course and others much more thorough. While a great option, this route will require two things. Time and money.
Language courses
Another, far cheaper and more flexible, option would be to check out the local city halls in your area. Often, there are volunteer groups and city sponsored Japanese language and conversation classes available. These can be very convenient and far cheaper, possibly free in some cases. You can check online for whats available in your area, though this might take a bit of searching and is easier if you know some basic kanji. It is far easier to just ask around though, especially at your local city hall since you have to go there anyway in the first 14 days to register and such. Near me, there were several places that offered many different options. One town had a classroom setup for groups to attend, much like the English conversation courses I teach for my local city in addition to my roll as an ALT at the Junior High School. Other cities offered one to one lessons with a volunteer where they would use whatever textbooks you provide in addition to conversation practice. The prices were all very reasonable too, anywhere from 1000 to 5000 yen a month. Of course some of these classes only met on Saturdays and/or Wednesdays, but it was a great resource.
Conversation Partners
By Far the most useful, in my own opinion, tool to learning a language is having someone to talk with. Its one thing to learn from a class or textbook, its another thing entirely to apply what you learn to actual conversation. Living in Japan of course provides you with ample opportunities, but only if you take advantage of them. I tend to find people to talk to when I travel. By trying to be warm and inviting and always airing on the polite side, I tend to be approached by people from time to time. Usually elderly who just want to talk or test their English, but others as well. Of course this is something that happens more outside the big cities because there people tend to value what little personal space they have so approaching them on trains might be a bit more rude. I always receive the same starting questions over and over, but don't get discouraged by it when you have to answer why you came to Japan for the hundred and twentieth time, instead look at it as a short review of basic Japanese skills before you level it up later in the conversation.
Of course you wont always run into people who are eager to chat, like the old man in the museum who approaches you because he is surprised to see a foreigner there, or the old woman on the train who loves your country's culture and keeps getting her granddaughter to help talk to you. Sometimes you might need to do a little legwork. This might mean finding a local English cafe or foreigner friendly bar. These places tend to have more Japanese people who actually want to talk with you. Of course you can just go to any bar or izakaya as well, there is never a shortage of drunks who want to make a new friend. Honestly, a bar or izakaya might even be a better idea if you are a more timid person, it may help lower your affective filter and make it easier for you. Of course you should drink responsibly.
Talking to strangers is one thing, but having a dedicated language partner who will actually help you and correct your mistakes is an entirely different thing. For this, you would typically need to take a class or find a language teacher, but there are other ways. Using language exchange apps or even dating apps, you will find no shortage of people who are wanting to learn English and willing to teach you Japanese for it. Yes I said dating apps too, i cant tell you how many people I talked to on those apps who were just there to find someone to teach them English. I am not sure all of them understood the purpose of some of those apps. In any case, whether you find a language partner through an app or by chance meeting, every encounter will help you develop your skills, and don't be afraid to make mistakes. Find what works for you, just use what you know and challenge yourself.
Speaking with Japanese friends can be a good chance to use the language, but they are unlikely to correct your mistakes or even tell you when you do something wrong. More likely you will just have them tell you that you are such a good Japanese speaker. "上手 上手です". It is safer to say that your Japanese is truly getting better when you stop hearing that and start getting into more conversation. Having a language exchange partner though will give you someone to practice with that will help correct your mistakes and make sure you aren't picking up any bad habits with your new skills. The point really is to just find a way to use what you learn and apply it more and more to your everyday life and conversations.
Helpful apps
As I mentioned before there are apps for smartphones and tablets that can help you as you learn the language. Whether to teach you vocabulary, support your studies or help you find a conversation partner, many can be very useful. Here are a few I have used and would recommend.
Japanese (Apple app store only)- My favorite Japanese/English dictionary. You can search by typing in the English or Japanese words, type the Japanese words in Romaji or kana, use handwriting to input the kanji, or even search for kanji by the components and strokes. Get the readings of the kanji or word, example sentences and uses and all the ways to conjugate the word as well. Save words into lists which you can use to create flashcards in the app for studying. Look up vocabulary sets by JLPT level.
Imiwa - This is a great alternative Japanese/English Dictionary if the Japanese app is not available to you. It has many similar features.
HelloTalk - This helps you find a study with a language partner. The app allows you to start with messaging and advance to recording phrases and even full audio conversations. The app includes tools to markup changes in messages to point out mistakes and teach the other how to improve.
Google Translate - Every language teacher will tell you that it will never give you a proper translation and often makes mistakes, but there are uses. For example, the camera feature with the live translate feature allows you to quickly get a general understanding of what is written. This is great for menus, store signs, shopping, bus routes, and more. Just don't rely on it too much. Otherwise it might hold your Japanese study back a bit.
Yomiwa - Another app that has the ability to do a live translation through the camera. This one however is a lot more useful for your studies. It doesn't offer a complete translation so much as a way to translate word by word while giving more info on pronunciation and kanji meanings. It also has a setting to help you read Japanese names.
Memrise - A spaced repetition learning app. Many vocabulary and grammar sets are available to choose from. The app will test you in a way that works what you learn into your long term memory. Set goals and use it on a regular basis to improve. It is not so useful to prepare for that test in two days you need to study for, but if your goal is to actually learn a language, then this is what you need.
LingQ - This is a language learning app that can really help you practice reading. It allows you to get content for your level, mark what you know and are confident with, and lets you hear and study what you don't. It also allows you to read along and adjust the speed, or read alone at your own pace.
A few tips
Use a document scanning app then open the documents with the google translate app to get a better understanding. Or open in the Yomiwa app to get assistance reading the new kanji.
Keep a small notebook with you to write down notes. Especially for new words or kanji you commonly see and hear.
Don't judge your own progress by the progress of others. Judge it against yourself and your own rate of learning. We all learn at a different pace, if you know more today than you did yesterday, then you are making progress.
Set specific and obtainable goals for your study. Then break those goals down into smaller and more obtainable goals. Having a clear goal and direction to work toward will help you when you inevitably hit a slump. It will also prevent you from suffering from not knowing where to go next. Using the JLPT is how I keep myself on track for my own study as well as check my progress. Measurable and obtainable.
If you are just getting started, there are many books and audio series out there to help. I started with the Genki 1 & 2 books and workbooks. I have also used the Minna no Nihongo series. These books give you a good starting point and solid foundation to expand out from.
Conclusion
Do what works for you. If that means paying to go to a language school, then do it. And remember that any progress you make will in turn make your life in Japan a bit easier. You can live and work in Japan with little to no Japanese ability, you can even have a fun time here, but the more you can communicate with locals, then the more you can learn and experience. Speaking the language will open many doors to new opportunities for your life or trip here. Be sure to use the resources around you to your advantage.