Its best to learn Japanese from a learning website. Learning websites teach REAL Japanese. Textbooks and teachers teach polite and they don't teach how people REALLY speak.
In the real world, people use slang, people talk differently. So learning from a learning website that teaches all aspects of how real speakers speak is the best.
These are the best website that teach FULL Japanese.
http://www.123japanese.com
★★★★★
- Teaches FULL Japanese lesson FREE
- Polite, Casual and slang Japanese (all Japanese)
- Fully explains lessons
- Teaches kanji and kana aswell
- Has video lessons
- Books
- Largest vocabulary list
- A forum
- Lots of other study materials
They also have a youtube channel
http://www.youtube.com/123japanesecom
http://www.japanesepod101.com
★★★★
- Has many lessons and study aids
- polite and casual Japanese
- unfortunately not free, you only get 1 week free trial (but just keep signing up with fake email)
http://www.maggisensei.com
★★★★
- It teaches random lessons
- Detailed lessons on wide variety of topics
- Casual and polite Japanese
- You can find a lot of stuff here you wont find anywhere else