In IELTS writing subtest, there are 2 individual tasks: Task 1 and Task 2.
Task 1 is a formal report and Task 2 is an essay.
It is often the case that the visual data which is provided to us to describe in Task 1 is very very little. Students simply don't know what to put into the answer papers.
One of the areas where you can get a penalty is your report writing being "Under length" which means you have not hit the target of 150 words, which will cost you very dearly. So let us always make it a point to write a little above 150 words, and an ideal length would be between 160 and 180 words, which should be your target.
Here are a few tips to do that:
Describe the action or trend taking place when talking about the numbers
You will notice that there is always a good deal of things you can say about the data in focus so it is always a good idea to describe what type of a change or a trend is being discussed. This will be much clearer with an example so let's have a look.
The use of bicycles had seen a dip of 62% over the years.
This contributes to about 13 words in my report. Now I can say the same thing but in a different manner.
The use of bicycles had a rather dramatic dip. It declined by 62% within a time period of 20 years.
This example provides me with an extra 6 words with just a little manipulation of the sentences. The same technique applied over a few sentences might be the difference between your dream score.
Paraphrase with no repetition
If you copy down the same phrases as given in the question the examiner will not count those words and if you are somewhere close to the border of the expected word count, this might end very badly for you. Thus, always use different words than the ones used in the question. include synonyms and if you are out of those, do not spend time pondering over it and move directly over to paraphrasing the desired word. Also, keep in mind to never paraphrase the sentence word-by-word and play around a little bit with the overall structure of the sentence. This also gives the examiner, a positive impression regarding your command over the language.