Note: I don't normally give the following advice to IELTS students. However, I think it's an interesting idea to consider.
Did you know that some professional English writers try to avoid using adverbs? Let's look at some examples to understand why they might do this.
1) Sometimes the adverb is unnecessary. Compare these two phrases:
- It is true that
- It is certainly true that
I often use the second phrase in my essays, but you could argue that the word "certainly" is redundant. If something is true, it's true! Do we really need to emphasise it?
2) Sometimes a single word is more descriptive:
- This is very important = This is essential, vital, crucial
- This is really difficult = This is complicated, complex, problematic, challenging
For our purposes, I think the second point above is more useful, because it encourages you to use a wider range of vocabulary to express ideas.
Remember: There's nothing wrong with using adverbs in the IELTS writing test. I just think it's interesting to consider the alternatives.