High scorers on standardized tests like the GRE (myself included) often suffer from a pitfall of sorts: they want a perfect score. Although that might seem like a good goal - and I suppose it's arguable whether it is - I think it can also be a detriment to performance. It may make someone inflate the perceived value of an individual question, and may also make it difficult to move on from a tough GRE problem before a solution is found - a solution that may never come.
Picture this: you've taken both PowerPrep 2 tests and gotten 169Q and 170Q. Then on the real GRE, you encounter a math problem that throws you off. You think about it, you try something... and it doesn't work. Now, you're conscious of the clock ticking. Damn it - why is this problem so hard?? Crapcrapcrapcrap....
Well, I've got some simple advice for you that may be easier to follow if I explain why it works. I know you know what I'm going to say: skip the problem, mark it, and come back to it after you do everything else that's easier.
Telling you to skip a question and come back to it is easy enough for me to say, but harder perhaps for you to follow. So first of all, you've got to actually follow that advice in practice if you want to execute it on the real test. Second, here's why it works: when you're stuck on a problem, it may be because you bought into your initial impression of it. This is, in a way, like going off your first impression of a person. And just like your initial impression of a person, your initial impression of a GRE problem might be wrong.
You may have misread something. You may have misclassified the problem. In any case, you current way of thinking about the problem may be handicapped by your initial impression. What works - sometimes - is coming back to the problem in a few minutes and looking at it with fresh eyes. This can allow you to evaluate it without your prior prejudice. This time, make sure you take your time reading the problem - I often catch students rushing to read things so they can begin working on them as soon as possible. But if you screw up your reading of the question, you're just going to create more work for yourself.
If you don't have time to come back to it - say it's the last problem left to do - try taking a five-second mental break. I'm serious. Think about anything else for five seconds. Then, pretend you're seeing the problem for the first time. Read it carefully. A way to solve it might dawn on you. I can tell you from experience that this method works - both for math and verbal. Again, if it makes sense to you and you want to add it to your bag of GRE test-taking skills, I urge you to practice using it, so it feels natural and normal to do on test day.
I also want to talk about a common scenario that happens even to some high scorers: the peril of "kind-of" knowing a concept.
Think about a person who is brand new to a concept - let's say, probability. When he sees a probability question pop up on the screen, he wisely skips it within 20 or 30 seconds, since he knows he has no idea how to solve it.
Now think about a person who "kind of" knows how to do probability questions. When he sees the same probability question pop up, he says to himself, "ah, I think I know how to do this", then proceeds to spend 2 minutes getting it wrong. The funny thing is, the person who skipped the question (and who ultimately had less math knowledge) is now in better shape, score-wise. My message to you is: just skip questions that you don't like. You can always try them later. But don't get questions wrong slowly.
As I tell my tutoring students, "you can't just 'know' a math concept to get a GRE question on it right... you have to actually be good at it - and you have to prove to yourself you're good at it through successful experience".
Now, I know it's not always easy to tell which questions will be tough for you. This is why, in the weeks before you take the real GRE, you need to practice and make lists of how long you spent on questions, what they were testing, and then determine if any concepts or question styles are things to avoid when you take the test.
Smart decision making is an important component of GRE success. If you have the willpower to quickly guess on and skip questions you don't feel good about, you'll be increasing your chances of a high score. Don't let overconfidence spoil your test day.