Talking, talking, talking. I'm a book study type of guy, but that really didn't cut it for me for getting fluent. I had a tough time "just talking", so I had to get thrown into situations where I needed to use the language in order to really practice.
This is actually the most important thing. Have an awful vocabulary, a rudimentary grammar, but get the pronunciation right. You can always buff up on your words or rules, but getting rid of an atrocious accent is very hard to do. Utterly impossible if you're Styrian.
I wonder whether singing helps. The overall musical structure might make proper phonetics easier to memorize; on the other hand I've heard quite a lot of people who can sing without an accent, but sound very differently when actually speaking. Maybe it is too much rote memorization.
I won't go as far as to say that singing is ineffective but, putting it at another way, you can sing in a foreign language pretty well without being able to speak that language.
