Go into the test knowing that you WILL be given questions you cannot do. The test has thousands and thousands of questions from which to choose and part of the test's goal is to find your limit. It will succeed - you won't be able to do everything. Recognize when the test has "beat" you and let those go!

And just to reiterate what Eric said, it's absolutely a myth that the earlier questions are more important. DO NOT spend more time on those. The myth started because some guys did a research study a long time ago showing that our scores would improve by 20 points if we got the first 7 questions in a row right BUT the study methodology assumed that you would NOT spend any extra time to get those 7 questions right. The study further showed that your score would go DOWN if you had to guess on 4 or more questions towards the end b/c you spent more time at the beginning.

In other words, the people who now say "spend more time at the beginning" didn't actually read the study methodology, because the score improvement shown in the study assumed that you would NOT spend more time.

The real study result is "The score improves if you get the first 7 questions right without spending extra time" - which is not a very useful piece of advice, is it?