Watching a whole lot of TV and reading a lot helps.. ^^;;
I'd watch hours and hours of Star TV or AFKN.. ^^;;
About books..
I started off with books like Amy Tan's 'Joy Luck Club'.
It was made into a movie, you know..
It wasn't that hard to understand either.
My guess is that maybe it's easy cuz it was written by a
2nd generation Chinese-American.
And once you get used to it, you can start reading books like
John Grisham's 'The Firm'. ^^
Or if all of these don't suit you, try reading a book that you've
already read in Korean.
For speaking, reading a book out loud helps =)
I've seen ppl who just attend english institutes w/o hardly any improvement.
It's important that you enjoy it and put effort into it.
Good Luck~!