Hi. I got a Band 9 in the IELTS, I'm from India and I've never lived in the US or Canada.
The key is self confidence, determination and concentration. If you're not comfortable communicating in English, you have to start PRACTICING well in advance. Read English magazines, watch English movies, talk in English to everyone, THINK in English all the time.
Off the top of my head, here are some important tips:
1. Writing: Break your topic answer into paragraphs and start each paragraph will words like "although, nevertheless, however, despite, etc." Let the last sentence of your paragraph blend into the first sentence of the next paragraph.
2. Writing: DO NOT MAKE SPELLING MISTAKES!
3. Speaking: answer all the questions that have been given to you, not just one or two. Use a lot of adjectives and descriptive words. But most importantly, BE CONFIDENT. Your confidence will reflect in your speech.
4. Listening: Focus! It's easy for your mind to start wandering when you're straining to catch every word on the tape for half an hour!
5. Writing: give different viewpoints on the subject being discussed and elaborate on each one. Make sure your content makes sense.
And for pete's sake, don't drink alcohol the night before or stay up all night studying! That's only going to get you down! Get a good night's sleep and have a wholesome breakfast before you go.
If you're not comfortable with English, practice well in advance and do a lot of the practice exercises online. That helps too.
Good luck.
Drea