Keep these tips in mind…
Remember, IELTS Speaking test is a test of Communication Skills, not about your general knowledge. We must focus on HOW rather that WHAT.
What if I don’t have information about the subject? – As long as you are speaking confidently, you are on the right track. You can suggest your opinion in case of doubt. For instance- Thank you for asking me this question…. but I fear I do not know much about this topic. Nevertheless, don’t mind sharing my views. What I estimate is …..,
What if I made a grammatical mistake? – Well, grammatical mistakes are sins. However, if you have realized your mistake then do correct yourself. There is no harm repeating your lines with corrected version.
Can I tell a lie? – Going back to the first question- IELTS is all about your communication, and not about testing your universal information. As long as you are able to convince the examiner about your reply, it is perfectly fine in Part II & Part III. DO NOT LIE IN PART I. It is all about your personal information.
What about my speed? – We, as speakers speak as per our audience, right? Imagine your tone when you talk to a baby or a friend or your colleague or the boss. Does the manner change? Indeed, you modify your language and speed as per your listener. Hence, when speaking to the examiner, don’t be too slow or too fast. Make sure your examiner is able to understand you without asking for repetition. Remember, it’s not important what you speak. What is important is ‘What the examiner hears.’