If you can, the very best way is simply immersion.
Move to the country and live there. Live with people, make friends with them. Ask them to speak to you only in their native language. Listen to their music and watch their TV and films. Read their books - above all children's books.
In my first four weeks in Germany I did a 4-week 'intensive' course that covered enough basic grammar and vocabulary to stumble through a one-on-one conversation with a lot of pointing.
After that I never looked at another vocab sheet. I could feel my brain soaking up the language day after day; I'd reach out for a word I'd never learned or a phrase I'd never used and find one waiting.
Obviously not everyone has the opportunity to immerse themselves in a foreign culture for twelve months, but if you do then just take it - time spent learning the language before you go is probably inefficiently spent if not outright wasted.
Unfortunately that's a bit difficult for us in the tech field, where English is often the lingua franca of daily work.
Ok, so my brain is soaking it up, but rather more slowly than I'd like. My ability to read and understand Hebrew has grown far more quickly than my ability to actually speak and write it. Too much of what I need to say and write all day consists of technical material for which even the local native speakers will switch into English.
It's not impossible to learn a language in your home country, but it's damn difficult. Most English learners reach a pretty good level even in their home country, but English is unprecedented in it's universality, usefulness, availability of TV, movies, books, everything.
For example, living in Sweden I was fairly fluent by the time I was 18 without ever having had a single conversation with an English speaker. I did what most people do, watch a lot of TV, then TV without subtitles, play games, write posts on online forums etc. The first time I had to actually speak it, I was 21 and taking care of an exchange student from the US. That year was what made me truly comfortable speaking English for days, without having to struggle for words and expressions.
It's that experience, and also spending 2 years at a US university and then working here, that made me a 98% native speaker. It's to a point where people can't tell that I'm not native now unless they spend a day with me. Some people sense that there's something a little off perhaps, still. I think the last 10-15% is extremely difficult to get for most people, without living in the country. A lot of that last 10% is cultural as well, there are still many cultural references that fly past me.
Move to the country and live there. Live with people, make friends with them. Ask them to speak to you only in their native language. Listen to their music and watch their TV and films. Read their books - above all children's books.
In my first four weeks in Germany I did a 4-week 'intensive' course that covered enough basic grammar and vocabulary to stumble through a one-on-one conversation with a lot of pointing.
After that I never looked at another vocab sheet. I could feel my brain soaking up the language day after day; I'd reach out for a word I'd never learned or a phrase I'd never used and find one waiting.
Obviously not everyone has the opportunity to immerse themselves in a foreign culture for twelve months, but if you do then just take it - time spent learning the language before you go is probably inefficiently spent if not outright wasted.