The IELTS Writing section of the test is the one that is most difficult for test takers to achieve a high band score and for examiners (there are two for each test) to award one. It is also the only section of the test for which you will need the help of an experienced tutor to help you by correcting your essay and commenting on your weaknesses.
While in the Speaking test you can easily assess your performance by watching the video or the recording of your practice test, there is no way that you can evaluate your own answers in writing and correct your own mistakes so that you can get a better band score.
Having said that, getting a band score of 6.5 is a relatively easy task, so if that is enough for you, you can prepare with the help of this short guide.
What the examiners seek is your ability to perform, in good English, written tasks that would be called for during your studies and /or work abroad.
IELTS Academic Writing part 1 tests your ability to extract information from a graph, chart, table or diagram, a very common task required for college students. You can find useful information and related vocabulary at http://www.ieltsbuddy.com/ielts-task-1-writing.html and
IELTS General Writing part 1 tests your ability in letter writing, which is a common skill required at any educational institution or workplace. Practicing on sample letters is the easiest way to get good results in this part or the test. You can use http://www.ielts-blog.com/ielts-writing-samples/ielts-letters-band-8/ielts-sample-letters-of-band-8/ and http://www.goodluckielts.com/IELTS-letter-writing-tips.html.
Based on these samples you need to practice writing as many paragraphs as you can around ten should be enough for a two month preparation, more if you prepare longer.
You will find the grammar points required for the first part of both versions (one paragraph of at least 150 words) at http://www.ielts-exam.net/grammar/
Writing an essay for IELTS Writing Part 2 is a far more complicated task, depending of course on what band score you are looking for. Along with your grammar and appropriate use of vocabulary, examiners will also be testing your clear understanding of the question and the precise delivery of your response and will give you an “impression” mark based on their observations.
This practically means that you cannot get a band score above 6.5 by copying pieces you have memorized from sample essays, even if your grammar and vocabulary is correct, simply because you will not be filling the requirements of the task. To get a higher score you must produce a grammatically flawless, vocabulary rich, and coherent essay based on language fluency, general knowledge, strong points and arguments, and wide writing experience.
Here are some links to help you practice: