As I said before, aiming high is great. However, you have to be realistic. Making 'stupid mistakes' is very likely to occur. Most of my practise exams I got 35 or 36/40 and for the real one I got 37 it seems. I was ranked in the top 3 in my school and my other 'high ranking ones' were all going on about how they would get like '50 easy', but I set myself the task of getting a 40, which is still a difficult mark to obtain (it looks like I should get it now though). Being... somewhat modest with predictions will help, for example last year I thought I'd get over 40 easily with business, but I ended up with 36. Anyway, this is a jumbled mess of ideas, so I hope you all get over the pain of disappointment and are able to focus on the next exam.