I'm a fan of the Princeton Review books (I used them for both SAT and GRE), but it's entirely up to you. I did very poorly on the math section, mostly because I suck at math, but rocked the other two.
For verbal, I went through as many word lists as possible and typed up a list of all the words I found that I didn't know, then posted it (in small print) in the bathroom for a very long time. So I had to study it every time I brushed my teeth, showered, went to the bathroom, etc... which added up to a substantial period of studying each day.
