R elax and try to be your natural self. They are simply trying to judge what kind of a person you are. Therefore, you should not appear to be tense or on edge.
Reflect before answering and consciously check yourself if you are talking too fast or too slow all that is needed is a little awareness of what you are saying an a little care on your part.
If you have not understood the question, do not hesitate to reframe the question and ask for a confirmation or some other device so that you are clear about the intent of the interviewer. You can even say “Beg your pardon” in a straightforward manner. Do not, however, do it too often.
Avoid giving an impression either of timidity or of brashness. The manner of your answering should be sober, balanced, and confident. Be, as far as possible, a good communicator.
Never, never bluff. There are five senior, experienced, knowledgeable persons interviewing you. You are bound to be found out. If you find yourself in a spot and do not know or do not know well enough about something, say so candidly. Your frankness may earn you a plus point.
Often a topic is followed up so that you will be required to elaborate or justify your ideas. As a simple example, let us say you are asked to name what you consider to be the three most important problems facing the country today, in the order of their urgency. No matter what your answer is you should be prepared to explain your choice and defend the priorities given. So before answering a serious question, think, consider and then come to conclusion.
In controversial matters, it is best to avoid firm expression or total disagreement with the interviews. If you are not 100% sure of your ground, it is a good strategy to preface your answer or comment with something like: “I could be wrong in this, but I do think that……”and then proceed to express your view clearly and with whatever you want to say in support.
As a rule, purely hypothetical questions are not asked in these interviews. But there are exceptions. For example, many a candidate for the IAS has been asked how exactly a given situation or problem would be tackled if he (or she) were the Collector/District Magistrate. If you confident enough to answer, by all means do give an answer.
Candidates, particularly those who are wanting to switch over from a profession or another Service to the IAS or those who have specialised in some technical field, are apt to be asked why they want to join the IAS. Be sincere. Say really attracts you to the Service even if it is nothing nobler than the prestige and security that it offers.