When you buy your books or CDs, buy lots of different CDs from lots of different companies.
The reason is that many CDs in Japan are written by people who don't speak English and hence they contain lots of mistakes, and lots of Japanese English.
Japanese English (Waseieigo) are words that sound English, but that native English speakers don't use and often can't understand.
Japanese English doesn't sound cool, so try and avoid it.
But if you buy lots of different CDs and books, you'll soon figure out which bits of English are real, and which are not.
Learn English that is cool, so that other people are so impressed they say “wow!” when they hear you speak.