Hello Pravin,
Like Swapna mentioned, this happens to all freshers. But also don't think that experienced persons are experts in handling interviews. You will surprised when you know the facts.
Coming to your problem/concern, FIRST & FOREMOST, PL STOP THINKING FROM THE INTERVIEWER'S PERSPECTIVE. Which means this: if you think/judge whether a particular answer will satisfy him/her, that's when your problem just begins. Every Interviewer has his/her own perspective--even if YOU THINK you have given the perfect answer, chances are very high that each interviewer will look @ it in a different way & give scores accordingly.
To give an example, you got 66% in MBA. I may think it's OK. Another one may think it's a very low %. And yet another one may rate it differently. AND YOU HAVE NO WAY TO KNOW WHAT THE INTERVIEWER IS THINKING.
Another important factor quite a few people overlook is that in an interview, MUCH OF THE INTERVIEW ASSESSMENT HAPPENS THRU THE UNSPOKEN WORD--basically the body-language of the candidate if it's a F2F interview or the tone & texture of the voice if a Telecon--NOT WHAT IS BEING SAID, BUT HOW IT'S BEING SAID [that's where Ramu's suggestion--be 100% confident--comes into the picture].
So from your preparation point-of-view, suggest FOCUS ON YOURSELF, YOUR STRENGTHS & MAYBE LIMITATIONS [wouldn't like to term them as weaknesses]. Brush-up what you know so that you can handle any question asked in those areas. If the interviewer asks something in IR & you aren't very good in that area, admit clearly & frankly BUT IMMEDIATELY FOLLOW UP WITH WHAT YOU ARE GOOD AT. Anyone will like when someone (1) admits what they don't know rather than beating around the bush or outright bluffing, AND (2) gives an alternative--and in a way you will be leading the interviewer in a direction where your strengths are from areas where you aren't confident.
This attitude/way-of-looking can be practiced by freshers & experienced people alike--in any domain/field.
Rgds,
TS