gmat prep

I’m thinking about starting to prepare for the gmat… if I don’t want to take a test prep course, what are peoples opinions on the best text to use (Princeton review, kaplan, official guide to gmat 800 q book, etc?) in general whats the best course of action for me to take without taking a course, and what do you think is a fair estimate of time required for prep? thanks

don’t know how this got posted here… meant to post in general discussion…