So you want to learn a new language and to do it fast? I don't blame you. Who doesn't? The only problem is that it can seem like a huge task to be faced with. So what if you are relatively impatient and want to learn as efficiently as possible so that you can become intermediate or even fluent in as short a space a time as possible?
OK, I realize that this sounds over-complicated but, trust me, it isn't. Basically, you need to mix it up. The more you mix it up then the more fun it is going to be and the less boring too. This way, you are more likely to succeed. Also, by mixing it up, you can achieve equal ability in listening, reading, speaking and writing. You do not want to end up with a deficiency in one of these areas because you didn't learn in the correct way.
Start With A Good Course
There are many courses out there and some are terrible and some are great.
In general, the best two are Assimil and Michel Thomas. If either of these providers do a course in your language then I strongly suggest that you pick them up.
Assimil makes use of something called shadowing drills. This course is considered by language aficionados to be the best one that there is.
Michel Thomas is a different course but also excellent. It involves no rote memorization or homework. You listen to the CDs/mp3s as if you were a student in a class of one teacher and two other students. It's a progressive course and you end up heavily using the language while you learn and it is simply incredible how well your memory retains the information. It is not heavy on vocab but instead the focus is placed on basic grammar and sentence construction. This means that if you learn more vocabulary later then you are already in a position to use it.
Thanks to the internet, it is easy to get a wide range of native media. I recommend starting with radio and listening to it every day. Don't just leave it running in the background but try to figure out what they are saying. The more "active" your listening, the more you will learn.
I also recommend listening to foreign music and finding the lyrics. My listening comprehension has increased radically when listening to foreign music, plus its a joy to do as well!
Movies and TV series are great if you can find them. If you can't find many then it may be worth simply doing the reverse i.e. watching programs in your native language but adding subtitles in the language that you want to learn. These are easy to find on the internet, just Google for "srt" which is a type of subtitle file.
When you get better you can also try foreign language books but I recommend holding off until you are at at least intermediate level.
Now I know what you're thinking: what could be more boring than looking at flashcards and remembering words? Trust me, I used to think like this to but it is actually an interesting mental exercise. There is also no better way to rapidly expand your vocabulary. A good course will give you the grammatical rules you need to learn for a language but without vocabulary you will be extremely limited.
Consider this: you need only learn 1,000 to 2,000 words to hold a basic to intermediate conversation. That's not as many as you think.
These days, you don't need to write down on physical flashcards with a pen. Instead, you can use modern and free flash card software. Just search for Anki or Mnemosyne. Anki is great because you also get access to free "shared decks" such as the most common 5,000 words in the language you want to learn.
If you want to learn a language fast then you need to study. You must accept this. Do not think that you can go to a country and immerse yourself and become fluent in a couple of years. I know people who have lived for decades in a foreign country and never picked up the language.
If you don't apply yourself and study the language then you may never learn it but you will certainly be slow in your gains. To learn a language as fast as possible, apply yourself in the way I have described above. The great thing is that this varied approach also keeps things interesting and prevents you from getting bored and losing motivation.