I learned that I had to take the GRE before September 1st in mid-August, so my studying was slightly rushed. I bought the Princeton Review GRE book because their SAT book is awesome. My mom is like a standardized test wizard, and she uses that book in the SAT class she teaches. I ended up reading through it twice, I think.
The verbal section of the GRE is fucking hard - a 740 is 99th percentile, compared to an 800 math being only 94th percentile. I wanted to really kick ass on the verbal section and make myself stand out, and I figured I suck at math anyway, so I spent way more time studying for the verbal section. I made flash cards of every GRE word I didn't know in my book, plus another book I got, plus any other word I heard that I didn't know. I also highly recommend supplementing a GRE book with the material that the ETS provides (scroll down):
GRE General Test: Prepare for the Test . Their review of math concepts was especially helpful to me. I did very little to prepare for the essays, because vet schools don't care about them. I read over the material for them in my book, but never wrote anything.
On the day of the test, there will be someone sitting two computers down banging on the keyboard like a monkey. Bring earplugs. I learned about 350 fucking hard words and saw two or three of them total on the test. Unless you really go for it, just straight up learning vocabulary won't be that useful, so maybe also focusing on learning prefixes, suffixes, and stems would be helpful.