ald is right, the computer test doesn't score based on number correct or incorrect. it starts the test with the average people are scoring at that point in time, so this can change slightly. if you get the first one right, it gives you a harder question worth more points and if you get it wrong it jumps down. the jumps will lessen as you get towards the end because the test is trying to place you properly. it's bizarre. i really suggest going to the free review sessions in the area (kaplan, princeton review). it will really help you understand the test. i went to a princeton review session that no one else attended, so i was able to get a one-on-one session for free that i think really helped. also, i think admissions offices take your percentage into account as well (most want to see at least 50%). and this will change with time, depending on how long ago you took the test. i barely hit 500 in verbal, but i was still at 60%, so you never know. and it's about the package. i was able to pull an 80% on the essay, so i'm hoping that'll make up for my verbal mush. personal business aside, i regret not having a stop watch in my face during practice because i was really anxious during the test. my advice:
1) get the book ets puts out with sample tests to practice in addition to barrons (my personal choice), the princeton review, etc.
2) practice with the computer program the ets sends you when you register and that might come in your book. it's helpful to know how the program works
2) go through writing an essay or two to work with the clock but don't get hung up on any one topic to study
3) as you get closer to the test, focus on your strengths. you don't want to do worse on the math section because you were studying vocab if you are a math student going into biostats. this is my scenario, and even though i learned a ton of vocab, none of my new words were on there and i was frustrated.
4) don't freak out if the questions start to feel really hard, it probably means you've done well and it's giving you higher scoring ones.
i did much better in practice at the end, but i think that's really because it came down to the pressure. plus, nothing that you study can give you the harder/easier questions like the computer will. i did what i could about my test anxiety. so be it.
