Interesting
This is an interesting one.
All through my life I've attempted questions in the order that they appear in the exams. Obviously if I'm real stuck, then I'd leave a space for me to come back to a hard question if I have time after I've done all the other ones.
I've managed to pass all the Institute exams aside from one, so this strategy has worked so far.
However, I was real surprised to find out that it is actually very, very common to do as others have said in this thread and attempt the questions in a non-sequential order.
I attended a workshop for exam techniques a couple of sittings ago, and the instructor mentioned that doing the harder questions first is a common strategy in case you are too knackered for it at the end of the exam.
Others say that it's better to do the easier questions first to gain some momentum and confidence.
However, I was too far down the line to change my methods, and kept attempting the questions as they appeared in the exam.
Also, I'm probably not a good judge as to what's an easy/hard question, so I didn't want to waste time procrastinating over that too.
The other thing I want to mention is that if I had a quick skim over all the questions and then tried to decide which one to do first, I'd end up having a lot of thoughts in my head about something tricky in lots of questions, rather than concentrating on the question that I'm answering.
SO, for me, at least, taking on the question without prior knowledge of what's to come has been the best strategy (ie doing them in the order that they appear in the exam - even in the first 15 mins of reading time for the later subjects, I've just used that 15 minutes to work on the paper from question 1. I write my answer on the rough paper in note form, and then copy it out onto the booklet when the exam starts).