First let me say that I am one of those people who do well on standardized tests. I work fast and maintain superfocus. Some people plod through, trying to be so careful, and I think they get bogged down. I also have a strong background in both math and English, so ... your mileage may vary.
Books, I recommend the Kaplan deluxe GRE book with access to their online tests and training. I was able to take a free diagnostic test too through a university. Don't bother paying for a course though. But Kaplan is really the king.
I also looked at Crack the GRE but I found their main advice was to plug in the answers in the math section. Kaplan says that, too, but it's NOT enough. You are also scored on speed, so you can't waste too much time. You have to be able to look at the problem, know what's being tested, and the answer will pop out many times.
(I did like the strategy to start plugging answers in the middle for certain types of questions; then if the first one doesn't work you can tell whether to try a higher or lower number so you plug in fewer numbers.)
Verbally, I have a strong vocabulary already but a lot of words I only know in context. Seeing them alone I don't know the meaning exactly enough to pick an antonym. So I (1) printed out the 4 pages of vocab words on Kaplan's site, signed up for two word-of-the-day lists (Merriam Webster and Dictionary.com, I believe), and looked up every unfamiliar word for about 2 months before the tests. I had people quiz me but they had worse vocabularies than I and they couldn't even pronounce anything so it didn't help a lot.
ALWAYS read the derivation (etymology). ALWAYS look at alternate meanings. TRY to learn words in groups of similar meaning (for example, words that mean "criticize"). I have a computer dictionary (Webster's New World) that has a synonym study feature, so for some words it will explain subtle differences between similar words. TRY to find the words illustrated another way, not just a definition or one sentence. For example I found a piece of art with "Calumny" in the title and I studied that painting!
I really hate the reading comprehension questions. I feel like they want me to read their mind. Also having to stop and read slows me down; I need to zip, zip, zip!! I found a lot of practice questions were poorly worded but on the real test it wasn't so bad. The exceptions were in the experimental section. I think one had to be 3,000 words long; I hated it. But I knew it was experimental so I just skipped through it.
For math, I focused on the things that seem important to GRE but I never really spent much time on in school. Probability and combinations, inequalities, basic geometry I'd forgotten, and sequences and series, to name a few. Know everything in the official GRE math prep materials: they flat out tell you what is on the test. Get to be really facile with exponents and roots. Of course you should know your multiplication tables, prime numbers, perfect squares, etc., as high as you can. Especially know the powers of 2 and 10 ... you should not have to figure what 2 ^ 5 is and how many zeros 10 ^ 8 has.
Practice a lot. Take as many tests as you can and go over the questions you miss. I used all the official Powerprep materials and booklets. If you're really pressed for time, don't even take the test; just look at the section that explains how they got the answer.
Also don't get discouraged with your scores on the practice tests. The real computer adaptive test is so different. I actually saw my raw score and although I only got one verbal question wrong, I got quite a few math questions wrong (and still scored 790). I even guessed at the last math one due to time. I think they didn't hurt my score because they were all 5 difficulty (they told me the difficulty). But had that been a paper test it would have scored me much lower. I was scoring low and mid-700s in most of my practices, sometimes as low as 690, and I was very discouraged! Luckily it made me study a little harder.
If you go to the test and it immediately gets extremely difficult, that's a good thing! You are getting questions right.