It's very important to support your points.
For example: maybe they ask you if girls and boys should go to separate schools.
If you're asked that, you might say: "I think girls and boys should go to separate schools for three reasons.
First of all, girls learn better when they're separated from boys.
In my own experience, when I was a student, I was always distracted by boys."
So you see what I mean? Give details, give examples.
Stick to the topic. This is very important.
If you're asked about education, talk about education.
Don't talk about your pets, don't talk about your hair; stick to education.
I think this is actually the most important point out of all of them: Think you will do well.
What do I mean by that? I think the IELTS isn't only testing you on your English, it's also testing you psychologically. Okay?
You need to think positively. You need to think you will do well. If you think you will do well, you will definitely do better.
Okay, another point: it's important to build vocabulary before you do the IELTS.
So you're being marked on four things.
You're being marked on pronunciation, you're being marked on grammar, you're being marked on vocabulary, and you're being marked on fluency and coherence.
So that last one is together.
So, these are the four different areas you're being marked in.
It's good if you focus partially on building your vocabulary beforehand; this is a good way to prepare.
You know you're going to be marked on this, so why not think about words that have to do with technology?
Practice these words in conversation. For example: "technophobe", "cutting-edge", "state-of-the-art".
All of these words will help you increase your vocabulary score if you're asked about technology.
Find words that have to do with education, with leisure activities, transportation. So this is a very important thing to do as well.