The first and foremost, and the most important thing is that you are studying for yourself, that studying is as necessary as eating, drinking or sleeping. A students main job is to study, do well in exams and prosper.
Once you have decided that you have to study, half the battle is won because your mind is fully prepared for studies. The next thing is that you should be cool. Not worried about the exam or how you will fare, or what will your parents say. Do your best and leave the rest to God and the examiners.
With a cool mind you should note what the entire syllabus of any exam is. Suppose you are studying History, you should be fully aware what the entire syllabus is. An overview of the subject is important. You should then find out how much time you have and divide your study time in such a way that all important subjects have ample time for studies. Dont get confused. If you are in the Twelfth Board exam and that PCMB are important, then allot more time for that. At the same time do not neglect your other studies.
A person I knew studied very well for the main exams but forgot(and was very confident) of the English language. He did not study much. He passed but his aggregate came down because of the language. Dont make that mistake. To pass in any exam you must have minimum marks in ALL the subjects. Even if you score cent percent in PCMB and get twenty five ine th lnguages, no one will pass you.
Make a time table. And stick to it. Give enough time for studies, first revision and second. Then you will be fully confident that you have done your best. Only studying is not enough. You have to remember everything. So have a good nights sleep before the exam, be cool and coinfident.
And when you get the question paper, read it carefully twic before starting to write it. Understand what is asked and how much marks are allotted to each question. If you write four pages answer for a two mark question, you are not going to get more marks. You will have wasted your time. Think intelligently and answer.
Dont be in too much of a hurry, otherwise you will skip some important matter. But dont dilly dally either. Divide the time with the number of answers you have to give and space your answers so that you answer every one of them. Then you can be assured of the best possible marks.
The correcting authorities are not devils. They are human beings. So a neat and clean paper will give a good impression and set their mood. Once you have finished a paper, do the post mortem only once and that too for a maximum of one hour. After that forget it and concentrate on the next.Do well and all the best for you exams.