Use headphones: YouTube and other streaming sites and music resources often have low volume and poor audio quality. Using headphones will help ensure that you catch all the words clearly rather than playing a guessing game as the song plays on.
Sing along: Simply listening to English music can do a lot for your understanding of English, but it never improves your spoken skills. To practice the words to songs yourself, you can sing the lyrics along with the music. There are also special karaoke videos you can find online that allow you to sing along to a version of the music without lyrics.
Pay attention to your mouth, tongue and lips: Notice how your mouth moves while you copy the pronunciation of the singers. This will help you transfer your English skills to normal conversations without music.
Replay difficult lines: The benefit of digital technology is that you can easily go back to a specific point in a song hundreds of times and listen to a part of a song over and over. If you find that a line has some difficult words, be sure to replay them so you can memorize them.
Practice speaking lyrics: You will not be singing most of the time you are using the English language! So after you have listened to a song, find the lyrics of it and read them out loud just like you would read a book out loud. This will help you learn to pronounce and use the words as you would actually do in conversation.
Have fun singing along!