There are many possible tips. The first and most important is to take it seriously and prepare properly for it.
These are all general tips.
1. In the exam – listen to and answer the question
The best advice for IELTS speaking is very simply to listen to the question and answer it. The reason for this is this is the one and only time you are face to face with the examiner and nerves are a significant problem. If you are trying to remember complex advice, you are likely to become more nervous and not perform to your best. Keep it simple.
One example here is in part 1. If you here a question in the past tense:
Eg “What sports did you play as a child?”
A good answer will use the past tense – the examiner will be listening for this.
2. Practice before the exam
Following on from the previous advice, you need to practice before the exam to make sure that the appropriate skills are automatic. This will only happen if you practice sufficiently. However, you also need to practice the right skills – each part of the speaking paper tests a different skill.
3. Immediately before the exam – speak English
The problem for many people is not speaking English, rather it is moving from their own language into English. The advice here is plain: make certain that you are already speaking English before you go into the exam.
4. Key advice – extend your answer appropriately
If there is one key piece of advice, it is to extend your answer appropriately. For example, this is inappropriate:
Question:” How many languages do you speak?”
Answer: “Two. Chinese and English.”
Better would be:
Answer: “I speak two languages. My first language is Chinese and I speak English too. I’ve been learning English since I was 10. I started learning it when I was in primary school.”
Be aware, however, that very long answers are not always a good idea. It is possible that you will go off topic and lose coherence.
5. Make eye contact
A large part of communication is non-verbal. You are marked by the examiner in the room and you should do everything you can to show that person that you are a good communicator. If you do not make eye contact with the examiner, s/he is probably going to be less impressed with your performance.
6. Do not learn answers
One temptation is to learn answers before the exam. Do not. The examiner will notice and your score will be badly affected.
7. If you don’t understand the question – ask
This is a speaking test and not a listening test. If you don’t understand the question, ask the examiner to repeat or explain it – you should not be penalised for this. If you try to answer a question you do not understand, you will almost certainly become incoherent.
8. Give yourself time to think – repeat/reformulate the question
In parts 1 and 3 you are not given any thinking time: you are supposed to start speaking immediately. This does not mean, however, that you need to start answering the question straight away. What you can do is start by repeating/reformulating or commenting on the question:
“What did I enjoy doing as a child? Let me see…”
“That’s not something I’ve thought about before. It’s an interesting question.’
This has several benefits. It is good communication. It allows you a little time to think. It should also make you answer the question and not the general topic.
9. Correct yourself – if you can do it immediately
If you make a mistake and you can correct it immediately, do so. This will show the examiner that you have control over the language. If, however, you are unsure how to correct yourself, move on: the examiner may not have noticed the mistake in the first place and if you try unsuccessfully to correct it, a small mistake may become a much bigger one.
10. Do not relax too much – it’s not a conversation
This is an exam and you need to show the best side of your spoken English. If you relax too much and become too conversational, your English may suffer. You need to recognise that this is not a true dialogue between two people: it is more of an interview with one person speaking and the other listening.
In a conversation the speaking conventions are quite different: you expect the other person to share 50% of the talk time and to react to your comments, typically one person will not speak for any length of time.