I use three languages. My first language is called Sundanese language (Basa Sunda). It's my ethnic language. Somehow I use this language more often than Indonesian until my college years because the most of the student in my campus is Sundanese. So, I used this to interact with my family and my friends.
My second language is Indonesian. Of course I've known this language since I was a kid but I only used it in formal setting like when I needed to present my work to everyone in the classroom. Basically, I've been frequent using Indonesian only since 3 years ago because I only met people who are not same ethnic. It was really not comfortable at first but somehow I can use it like a real Indonesian lol. I learned this language by interacting directly with other people of course.
Then my third language is English. English is one of main courses in schools. But, the studies were not effective. It looks like I only learned about basic grammar and that is. My English was really horrible (now it's still bad though). I couldn't understand what the speaker said in the final English test even though she/he talked so clear. My English was improved because I watched so many Anime and Japanese drama in college. The subtitle was always English so it can't be helped, I need to understand the subtitle if I want to understand the story. I remember the first time English subtitles that I needed to read frequently was Naruto. So, I needed to pause and looked the dictionary (it was a real book dictionary since the we didn't have google translate in 2007). So, I think this is really effective. My nieces are also good at English since they are more familiar with English subtitle. However, the only bad thing is that we are terrible if we talk with English because we never have a chance to practice. I think this only will be good if we have an environment to talk with English regularly.