May be you can try the following way to learn a new language faster - I find Internet free translation software e.g. www.babelfish.com etc. provide very useful tools to learn a new language. They can translate sentences from 1 language to another not only in terms of writing & grammar but also in pronunciation.
I remembered working in 1 international project in which 1 of my colleagues having difficulty using English to communicate. We found babelfish really help us to converse and understood each other effectively. In fact through babelfish, it enhanced my curiosity to learn the particular foreign language better.
Moreover, wherever country I'd landed in which English is not the common language, picking some of the local key terms in local language through Internet is extremely useful. Wishing you all the best.
I think it would be a useful first step to decide what you need the language for. This will help you narrow the focus of what needs to be learned and thus make the task easier.
If you want an answer that represents teenagers, here is the answer.
The most commonly used way is reading subtitle of the movie (in your desired language) two times. First, in our mother language, then in its original language to check the right pronunciation. The other way is, talk in the desired language frequently.