Hi,
I read various sections of the New York Times everyday for a month and a half. Articles from the front page, the arts section, the science section, the editorial, and the book reviews. I spent like 30-45 minutes every morning doing this. In addition, I did Princeton Review practice passages and questions every day. My score on the VR went from mid single digits to a 12 in a month and a half's time.
This is just the strategy that worked for me, but I think reading the New York Times or some other paper or opinion magazine (with a moderate to difficult reading level -- NOT cnn.com or something like that) at least gives you some practice on topics with which you may not be very familiar. Later on in the day,while in the car or waiting in line at the bank, test yourself on recollection of details in and on your comprehension of the articles you read.
I agree with surdevl02 that the Kaplan passages aren't that helpful.
Hope this helps,
--Vinoy