Nothing beats the ETS Powerprep software to give you an accurate feel for the questions. I used both Princeton and Barron's to study and there were still things in the ETS quant questions that hadn't been covered by either book. Plus you learn the kinds of tricks and problem solving methods ETS wants you to use. In addition to the two practice tests, there are several sets of practice quant questions, which I found very useful, and which shouldn't be missed.
Word lists: I was already scoring high here on the practice tests, so I didn't spend as much time on it, but I did make a point of writing down and looking up every word I came across in every practice test that I wasn't solid on the definition of (even if they weren't in the question, or weren't the correct answer). For the word list I assembled over time (from both published word lists & tests), I made flashcards that included the words used in sentences -- to find those sentences, I searched Google News for each word, to find it being used in context! This is the best way for me to stick the word into my memory; nothing sucks more than getting a word you know you've studied, but you can't remember the meaning.
Practice pacing! Also be very familiar with the need to be slower and more careful on the earlier questions, since they affect your score so strongly. The Princeton Review book even has a handy chart that shows how many questions you should do per 15 minutes of the test based on your target score (including 800s).
DON'T waste your time on the GRE's published book of tests -- all the tests are 20+ years old and the types of quant questions are way too easy and don't include a lot of more recent things like stats, graphing, etc. Total waste of money and hours.
I think what tripped me up on the verbal section was a couple of uber tough reading comprehension questions nearish the end. There were at least two questions where I could CLEARLY make the case for more than one answer being correct, so that was frustrating (especially since I was an English major!). I'm not really sure how to study for that besides saying prepare for the need to discern nuance.
I ended up with a 1550 (790Q, 760V) (a huge, pleasant surprise!), so good luck. :)