How to improve your listening skill?

Many people struggle with their listening skill. I have been struggling with listening about 3 years and eventually it got better and better. I've done following things in order to boost my listening skill.

1. Watching serial movies with subtitle. I watched Friends (like 20 times), Gossip Girl, Desperate Housewives, Sex and the City, Game of Thrones (MY FAVORITE ONE) - Highly recommended
2. Always listening to Billboard hits and memorizing its lyrics
3. Lately i've been listening BBC radio online. If you have internet connection then while you are checking your emails, FB whatever, it is not a big problem right?
4. Try to watch TV programs in English.