Its not easy by any means. Firstly you obviously have to know absolutely every bit of content you can know. Secondly, you have to practice practice and practice some more. Personally I practiced by just doing virtually every past paper but I also did some of them in challenging ways, like for c1 for example I would try and do the paper quickly and then in the exam when I had another hour more than I would normally it would feel easier. For the exam itself, i have several recommendatioms. Firstly, where possible learn how to do a question in more than 1 way. If you can do a question using 2 different methods and get the same answer than unless you've done something very weird than your answer is right. Secondly, lwarn how to use your calculator to check answers to trig questions, integrals etc etc. Lastly, no matter how much you prepare you will get stuck. For me persinally the best way of getting over this is ti take a step back from the question, and almost have the arrogance that you've done almost every question so no matter what they can ask you've done a similar question, you just have to work out which method you've done before you need to use. That way you can remain calm and hopefully you'll then be able to answer the question. Hope that helped somewhat