In Korea, one of the most popular 방 (room) is 노래방 (Karaoke room). A lot of pre-debut celebs frequently practice singing at nearby karaoke practice room or the coin karaoke room. The difference between the two is: Karaoke: You pay per hour and you can sing as many songs as you want. There are deals where you pay a fix amount for 5-6 hours. It's a good option if you have the time to spare. Btw, young people usual go to 노래연습장 (norae yonsup jang) because 노래방 (noraebang) gets a reputation for drinking/singing in Korea.
Coin Karaoke: You pay about $1 for two songs. It's a great option, if you're slow at picking song or don't know what to sing. You don't get charged for amount of time you're staying in the room.
If you don't live nearby a Korean Karaoke you can always DIY at home! There are tons of karaoke music videos on Youtube. The only con is you can't get a singing score.