Hi Misa :)
Scientifically, moving to that country where they speak the language would be the fastest and quickest way to fluency!
Alternatively immersing yourself EVERYDAY in the language is the next best option.
Here are some examples:
-Skype sessions with teachers and community tutors on italki.
-Watching movies, TV, podcasts.
-Written diary entries.
-Podcasts and audio books.
-Reading (Magazines, newspapers, books).
-Practice with friends in person or online (pen pals).
Remember the fastest way to fluency is to practice everyday. italki is a brilliant resource for this.
I hope I have helped you.