BEST METHOD EVER! I'm currently learning a language faster than I've ever learned one before. I hope you read this as I tried every fucking method including rosetta stone and duo lingo and they all suck. They are good for a bit but then it gets too complex for the app to teach you and you lose focus. I'm going to explain what I've done to learn Italian. I've been learning for about a month and I could easily live in the country now. Look at my post history to see what level I'm at.
Here's how I've done it.
Read this to start.
Download an app called SuperMemo.
Input the 100 most common words into the app as flashcards.
Learn the flashcards everyday until you know them.
Learn this list of words by using the flashcard method
While you are learning these words over the next month or so you should immerse yourself to radio in your desired language. Listen to the foreign radio when you wake up or go to bed. TuneIn Radio app is amazing for foreign radio stations.
Read news websites in that language. Subscribe to subreddits of that country e.g /r/italy for me. Post in that subreddit!
Join lan-8.com and find a penpal on there and message eachother on there everyday!
Once you have learned that list of 625 words then you move on to bigger lists, and you keep doing this. I have only been doing this for a month and I could have explained a lot of this in italian. It honestly is really easy! You must want to do it though, it should never be a chore! It becomes extremely rewarding!
One big tip for learning vocab which has helped me hugely = create vivid associations in your head to help you remember words. For example I had trouble remembering that 'quale' meant 'which' so I created an image of a witch on a broomstick throwing quale's eggs at people and now I know that 'quale' means 'which' because I always think of that witch haha. Another example is 'qui' means 'here' and I struggled to remember that, so I just thought of me saying to my girlfriend 'don't queef (qui) in here'. Now I know that 'qui' means 'here' because I think of my girlfriend queefing in here. It sounds absurd and it is but it works man!
I highly recommend reading language learning guides by Time Ferriss and Benny Lewis. They have managed to learn a shit load of languages by doing it this way. Cut the crap out and just learn the most common words used in the languages and immerse yourself in the language. It's easier than you've ever realised :P