Total immersion

Egg   Mon Dec 10, 2007 6:19 am GMT
I've been living in Canada for almost 10 years now, but my English, especially spoken English, isn't as good as it should be for someone who has lived in an English-speaking country for such a long time. I can't help using my native language when I'm thinking or before preparing to talk with another in English.
What are some ways of totally immersing yourself into English?
When you do this, do you have to completely stop using your native language?
For how long should you do this to actually be as good as native speaker?