Good tables and chairs - I HATE when the table or chair has uneven legs. Everytime you write, it moves around. The smoothness isn't that important as we have writing pads anyway. Even if we write on the actual question paper, we're still given the paper so I can put it under if needed. We've never had a table collapse during an exam, I think it's happened once before the test started.
Silence - As quiet as possible. I hate when the rest of the school are walking around behind the stage >.<" The back of the hall is the office so that end is not very noisy, but the front is the worst with people going behind the stage to get to class. They only close it off for the HSC and possibly the trials, I don't remember. The chemistry exam had someone drilling outside! It was such a headache >.<" It's good how they turn off the bell and everything in the hall though.
During exams, what I want to hear are turning pages. I like to know how my pace is compared to other people xD
Clock, start & finishing times - Clearly shown, for obvious reasons.
Flickering lights - I hate flickering lights anytime. They make me dizzy @_@
Temperature - I can't write properly when my hands are cold, my writing goes all wonky like a little kid's. I don't want it too hot either because that's just uncomfortable. Last year's English School Certificate trials were on a hot day. It really felt bad.
Teachers - I HATE when it feels like they're looking at your paper or what you're doing. It sucks if you have no clue what you're doing. In the Chemistry exam I was drawing a diagram that I thought wasn't confident about and a teacher walked past D: One chuckled in front of me at that same exam o.0 I think it was at my friend but still, I didn't know at the time!
In the Chinese exam, I looked at the dictionary constantly and I felt like the teachers were judging me. I don't have mental problems by the way xD