So how to get from 0 to 24?. I'm really no scientist, but I think of it as the same way a baby would learn a language. you get yourself in an environment where you try to submerge yourself into the language. The "mum" here should be something you really love, for example a TV show or a movie or a radio show. The other ingredient would be to get the basics of the new language first in term of grammar and words. I would say a few hundred words that are important would suffice at the beginning. The trick is not to learn word by word, but rather sentences (I think of them as the algorithm of each language). Subtitles for me at least seem to hinder the brain of connecting speech, facial expressions, feelings, images etc and blending everything in a perfect place for the brain to remember. An example: In German "Gift" means poison in English. However, As a native English speaker your brain is wired to think of it as something positive, because all of the memories you had when you received a gift. So instead of translating it, remember it in the original language with original memories/images/sentences.

Try also to read a lot of pop culture magazines. This is really important because it helps you understand slang, inside jokes..etc. An example: Would you be able to understand a joke about Bill Cosby/ Justin Bieber if you didn't read those pop culture magazine?

Finally, your speaking need practicing by talking to native speaker and going to meetups/get tog ether's to practice.

Once you get the above, just have a little faith that it will click. Keep watching/listening and you will at the end understand what the "mum" is saying :).

Edit: This method is based on Images and Emotions which scientifically have a bigger impact on us than just words. Can't find a link to an actual study though.

Hope this helps.