A lot of people ask me how I came to speak such good Korean...especially since I've only been studying for three years (which is actually really only 2 years since I stopped for a year or so in the middle while I was in China).
I firmly believe that is has a lot to do with the fact that before learning Korean, I spent a lot of time around Korean people. My close friends in high school were Korean and they used to talk to each other in Korean all the time. I gradually learned to follow conversations, understanding through intonations and parroting what I'd heard.
In my opinion, this meant that when I eventually began to study Korean a few years later, I already had a gut feeling for the grammars and structures and I could, to some degree, see patterns in the language.
In tip#1, I suggested listening to the radio but it doesn't just have to be the radio - anything which increases your exposure to the target language will do so tv dramas, podcasts, music, anything.
However, when you're listening, make sure you really listen. Think about what is being said and try to understand it as much as you can.