Today was my date with GRE exam ;). Though I didn't score as much as I was expecting, I liked the way this exam is conducted. You may be aware that it is computer adaptive test i.e. difficulty level of next question depends upon the correctness of your previous answer. Also, you cannot go back to a question and change answer. Though this was known to me even before I registered for the test and I had appeared for many practice tests prior to the exam; I don't know why, I kept thinking about this feature for an hour or so after the exam. It was quite appealing to me because later, I arrived at a conclusion that this exam bears a great amount of resemblance to the life we lead, barring eccentric exceptions.
1. You can never go back and change your answer.
(You cannot go back in time and do whatever you "should have". You are bound to face consequences of whatever you do (or don't do) in the past.)
2. Attempt your first few questions properly. They matter the most. However, it is important not to get disheartened if you are not sure about one or two. It is not necessary that all of the initial answers 'must' be correct for a reasonably good score. Also answering them correctly doesn't guarantee very high percentile, you may spoil it later in haste.
(Yeah, as they say, first impression is the last impression. But of course, we do know, it is not always the last impression, you can always spoil or make up your image.)
3. If you answer correctly, you should expect next question to be slightly tougher than previous one. If you don't, expect an easier question.
(When you manage to do some work properly, people around you expect you to do even more difficult tasks. Your deeds only raise or lower their expectations).
4.Therefore, getting harder questions is more beneficial than getting easier questions.
(Greater the responsibility, higher is the social status and also.... income.)
5. There is an unidentified section in the exam that is not scored. One is advised to attempt all the sections with equal attentiveness. You never know what is going to count and what is not.
(Legendary quote in Bhagvatgeeta "कर्मण्येवाधिकारस्ते मा फलेषु कदाचन" or simply put: Do your job, don't look for profit or gain when you are doing that।)
There may be even more, but I thought of only these.... :)