It is important to know precisely what the topic is, and what the question is concerning that topic.
Look at following IELTS writing topics
1. Studying the English language in an English-speaking country is the best but not the only way to learn the language. Do you agree or disagree with this statement?
2. The world is experiencing a dramatic increase in population. This is causing problems not only for poor, undeveloped countries, but also for industrialised and developing nations. Describe some of the problems that overpopulation causes, and suggest at least one possible solution.
The first one is “studying the English language in an English-speaking country”. The question asks you to consider the alternative: studying English in a non-English-speaking country. I would recommend you compare the advantages and disadvantages of both ways, otherwise it may most likely mean a lower score.
The topic in the second one is “overpopulation”. If you wrote at length about overpopulation not being a problem, it would be irrelevant. In addition, you would score less if you failed to offer a solution.