I live in Japan at the moment, and a few of the things that have helped me along the way:
Learn Hiragana and Katakana before you arrive. Well before you arrive. It'll help you navigate stations when you take the trains and be able to read some of the items on the menu (but the majority of the written language is kanji, so dont expect much more usefulness than that). Also, if you study here, all the books will be taught in hiragana from the offset, so best to get some advantage.
Whatever words you learn before coming too, shouold be kept in a notebook, in hiragana. Your knowledge of kanji from China should be really useful. Just a matter of learning the correct pronunciation.
I'd recomend studying and completing the first "Japanese for Busy People" book before you arrive too. Learning how adjectives and verbs work before you come and learning a few and how to change them to the negative and negative past etc. will put you on good ground. I spent a lot of time just trying to get the rules straight in my head before I could think about using the language flexibly, so if you already know how it works, it will be easier to pick up and use new vocab straight away once you're here.
You should really try some language exchange. There's no shortage of Japanese people who want to learn English. Getting the pronunciation right from the beginning is vital. There's no stress in the language, and so when we put stress into Japanese words of more three syllables for example, it sounds totally different to how it should. There arent that many sounds in the language, so if you have a good model at the beginning, then it will never be a problem in the future.
As a general point about language learning as a whole, I would say that a good notebook, with words grouped into noun, adj, verb etc. is important, but also, make "themed" pages too, like; words related to family, time, probablity, movies, weather, illness, similar sounds or easily mistaken, etc.
It can be motivational to keep and update and draw in etc.
At the end of the day, it depends on how long you want to stay in Japan. That will decide how much effort you need to put in. It's not incredibly useful anywhere else in the world, and it's perfectly possible to live in a "bubble" of English anyway. Generally, the people who will approach you to chat will be people who want to speak English, and if you only need English at work too, then it will actually be a challenge to find situations to practise anything more complicated than the usual daily expressions ("this please" "thanks").
On the flipside, by making the gesture, and trying to do things that require you to use the language (I do aikido in a small dojo where only one guy speaks English, and I want to speak to them because they are now my friends) you will gain respect for trying and inevitably be able to have a wider experience.
But you live in China! and probably know most of this already, so forgive me if I sound patronising.