1. Your basic intelligence (in Quanti and Reading Comprehension)
2. Your speed of responding (that's why the time limit is kept...and so, many of you who are practicing for the GRE must be finding difficult)
3. How well you perform under pressure? And also I used Barrons and Kaplan tests and bigbook. All these material are no longer useful as ets had tremendously increased the difficulty level of questions especially the quans and the reading comprehension questions.
If you are pretty clear in the above things then a good GRE score is not that difficult.
First and foremost suggestion:
Don't get tensed up. Remain cool and calm. Sometimes the only difference between a good score and a bad score is your mental strength. Just chill. No worries, no tension. Talk to yourself. Tell yourself that you can do it. If you win over your tension, then GRE is a piece of cake leading to a good GRE score.
Practice is the key to success. Give as many practice tests as possible. Grebible and Powerprep are a must. You can also try out Arco.
Practice tests and the CAT tests in grebible are excellent. The difficulty level is very very high in grebible. That's the reason why I was able to score much in the verbal and in the quans.
If you go without giving practice tests, that too practice tests with difficulty high level of questions. Your chances of good GRE Scores are negligible. You will end up with a average GRE score
The main advantage for me was that I got 4 analogies and 2 sentence completion questions straight from grebible practice tests. These questions were within my fist 10 questions. That boosted my gre score. Thank god else I would have been sitting with computers and doing silly things in my office.
PowerPrep gives you the exact GRE Score which you will be your GRE Score plus or minus 10 - 20. Your Gre scores from power prep will be an exact replica of your actual GRE score.
I had no time to study for gre as my work is very hard. I used to come home only at 11 or 12 or even 2 in the night. But it was a passion for me to study MS. Initially it was very tough for me to find time for me to prepare for gre. I prepared very slowly for gre. Started with Barron's wordlist. After completing them when I took a diagnostic test, I was shocked at the results. Then one of my friend suggested Gre Vocabulary Bible from grebible. The software was cool.
Some General Tips:
1. Complete the math review in barron's with the exercises and also the one given by ETS.
2. Do math exercises in grebible. I found grebible math to be toughest of all.
3. On the day of test, free yourself from driving to the test center.
Take an auto or better still ask someone to drop you.