First u should try to find out in which subject u have command try it first and then allow urself a minute to think about the question and then answer it.Secondly if u find that u are not able to answer some of the question then leave it and then again go through it after completing the paper and then start thinking again about this.Thirdly, do not loose ur confidence if stuck somewhere between the question.Do paper with full concentration.Be cool and relax for ur exam..All the best!!!!