GENERAL TIPS
Success in the IELTS exam requires a candidate to know the test format and the specific techniques for answering questions. Make sure you are fully equipped with this knowledge. ( Please see Resources on the Internet and Books )
Don't believe people who tell you that IELTS needs no preparation if your English is good. Even if it is, you still need to learn the right skills for the test. I would suggest a period of two weeks as preparation time, though this would vary depending on your level of familiarity with English. The test fees are high and if you don't get the band score you need, you have to wait for three months before you can take the test again.
Like in all other exams, practice is the key to doing well in the IELTS. Make sure you have plenty of it before you appear for the test.
Answer all questions. There is no negative marking for incorrect answers.