As you have attended coaching classes, you have a fair idea of the exam and interview.
In competitive exams what matters is to be the top of the lot. You should not underestimate or overestimate the competitors. Almost all are of same age group, qualification and knowledge. The core point is who scores bets at that time when exam or interview is conducted.
Practice is what matters and makes you prepare for the test. Speed and accuracy is needed in the tests. For that much practice is necessary. You may have to work on all the guess papaers, earlier year questions(if available) etc. Good coaching classes give practice in this regard. Once the pattern is well understood, it needs constant practice and repetition to get speed.
General knowledge, as it clearly is, is just general knowledge. Much of it can be obtained by regularly reading one or two good newspapers and following one or two good news channels in TV. If one of them can be English, that will be an advantage. For brushing up the knowledge learned and forgot, you can read one general knowledge book or magazine, if needed.
Interview is mostly impromptu. Very few questions are kept ready by the interview board. Most others are coming from the responses and the bio-data(resume) one submits. One has to be sincere, truthful, decent and civil in behaviour and communication. One should not try to bluff on something one does not know at all. One has to be positive minded, and not to complain about the existing employer or job if one is already working.
Some knowledge about the institution one goes for interview is good. One has to be relaxed and realistically confident. One has to be more thorough if one has projected any one field in his resume.
