1) Download Textbooks
If you are starting to study Japanese from scratch, please download these Textbooks.
Japanese Basic-I and Reference Book Basic-I
from textbooks download page.
2) Watch videos
If you are interested in mastering Japanese characters, Hiragana and Katakana,
watch “Hiragana & Katakana” video.
Greetings are always important when you start learning a new language and culture, so
watch “Greetings in Japanese” video.
Without having vocabulary, you can not make sentences or catch what people are saying,
so please try to memorize as much vocabulary as possible.
Watching vocabulary related videos is not enough, so also download a dictionary app into your mobile phone, and create a habit to look up unfamiliar words.
3) Use it
Please try to use what you have learnt. Even if you do not have anyone who can converse with you, please try to repeat the sentences to yourself.
Finding a speaking partner online is also another alternative. But please always remember to ask your parents if you are underage.
You can also think about having online lesson to put what you have learnt into practice.
4) Other sources
There are many other sources to study Japanese such as YouTube videos, websites, podcasts and also Apps like ANKI(means learning by heart – flash card app).
One of my recommendation is Meguro Language Center. They have many studying materials, which they have allowed me to use for my lesson as well.
Regarding dictionary App, I use Japanese for iPhone, and JED(Japanese-English Dictionary) for Android phone.