영어구사가 능숙해진 본인만의 비결이 뭐세요?

"There is no royal road to geometry." - Euclid.

Reading a lot of English novels helped in my case. Start with short stories first, so that you can feel the achievement and have fun. Don't try too hard to understand every sentence and memorize every new word; that will wear you out quickly. Just read on and enjoy the story. Gradually you can move on to longer, more difficult ones.

For listening, I recommend watching some American drama/news. (IMHO, American dramas pose widely different levels of difficulty for non-native speakers. I found "friends" one of the easiest: people don't speak so fast, and there aren't much technical jargons.)

Unless you want to be an actor or politician in the English-speaking country, writing will be more important than "native accent." So screw with native accent. Very few people can master it after puberty, and it's really not worth the effort. As for writing, it's the hardest part because somebody has to read the crap you write and correct it. :/ In my case that was my advisor (I went to a grad school in the US), but not many people can choose that path. Well, there should be some kind of service where native speakers look over your English writing and make suggestions. Or, if you have some basic reading comprehension skills, just reading a lot in English message boards (and occasionally commenting) can help. You can even join a flame war... that way you can learn a lot about good expressions to use. Just make sure that your employer doesn't know what you are doing. :P

* And, finally, because this is very important, I'll repeat: there is no royal road. Anyone who thinks there's some universal magic formula that makes foreign language learning easy, is deluding him/herself.

People learn native language as the sequence of Listening-Speaking-Reading-Writing in native environment.
But, We are learning foreign language as the sequence of Reading-Listening-Speaking-Writing in our living environment.
If you listen native language in native environment, you can remember it easily.
But, If you read foreign book in your living environment, you are hard to remember it.
A few weeks ago, I saw Park-Ji-Sung speaking English fluently on TV sports news.
I was greatly surprised to hear his speaking English.
I realized that speaking native language in native environment is very important.

PS: I take a lot of times to write above sentences. It is very difficult for me to speak Englisgh.