Japanese is a hard language, you can't just learn it in 3 days. But before going to Japanese classes you can try learning "at home" these things. It will be much easier for you.

Step 1: Research

Before learning Japanese you need to know something about it. Read about the history of Japan, read about the writing, etc...

Step 2: Learn About the Alphabets

You first need to know that the Japanese language has 4 alphabets. Hiragana (the easiest one), katakana (the one that is sharp and very easy to read), kanji (the Chinese alphabet, the hardest one with more that 2000 characters) and romaji (the one that you can read it without knowing any Japanese characters, is not with Japanese characters, is with letters).

Step 3: Practice

You can make a little "calendar". On that paper you can write: the numbers 1-31 and days of the week. When you will wake up you can try and say which day is it. Don't panic if you don't know where to find them, there are a lot of sites that can help you with that.

Step 4: Writing

Now you can start practicing the writing. Start with hiragana. Take a piece of paper and a pencil. Write for each one what letter is it. If you find it too hard to remember all of the characters, you simply just put someone to ask you what is what. After you know it and you can read it very good, you can start learning katakana too.

Step 5: Learn

You need to learn how to introduce yourself and how you can ask certain things. For that you can watch a lot of videos on youtube, they are Japanese people that are helping you with those sentences or you can print some sheets and just learn them. And don't forget about vocab words.

Step 6: Anime

Probably you won't believe this but watching anime is one of the fastest and easiest way to learn Japanese. You will learn a lot of new words and phrases (you can write them down on a paper) and if you want to, you can try watching them without subtitles.

Step 7: New Words

The best way to learn new words in Japanese is to stick a piece of paper on every object in your house and write what is that object in Japanese. For example, "door" in Japanese is "doa" so you can stick a paper with "doa" on your door. And also you can write in hiragana underneath.

Step 8: Reading

A good way to practice reading is to just read from an dictionary, you are improving your reading in romaji and you found out new words too.

Step 9: Practice Every Day

If you keep doing this I am sure you can go to Japan and talk to somebody about you and what you like, etc... Japanese is a very difficult language, you can't learn it in just 8 steps, you need to practice, if you are not practicing you can forget it very quickly.