I think it'd be difficult for anyone here to recommend any plan of actions or books because you haven't provided enough inputs. I'm not sure whether MGMAT GRE books are good enough to tackle GMAT. However, from what I know, GRE and GMAT are two different exams. GRE is more vocab centric while GMAT has a more comprehensive Verbal section. Though I haven't been in-depth through GRE Quant, but if I remember correctly, all of my friends who'd taken the GRE used to say that the GRE Quant is a cakewalk.So you need to have a different kind of approach,different set of books, strategy etc for the GMAT.

Great feedback, Rishi - I'd also add that the GRE is much more a "knowledge" test while the GMAT is more a "reasoning" test, so even on the math side on which many of the skills are similar, the GMAT requires a lot more flexible thought. Data Sufficiency, for example, is right around half of the GMAT math section and does not appear on the GRE; DS questions are fantastic at neutralizing "pure math" ability and requiring people to think analytically, so the skills that are required to succeed on a GRE problem may only be the price of admission for a tough DS problem.


My advice to kevtims - break down your GMAT performance by topic:

-Concept areas
-Question types
-Recurring errors

And build up a plan from there. You may find that certain concepts that aren't tested on the GRE are items that you simply need to study and master. You may also find that many of your recurring errors are question-specific (say, assumptions on DS questions) and improvement is more a matter of learning to anticipate and minimize those errors. Your first step is to be analytical in how you assess your performance to date - GMAT scores are not linear, so it's hard to say that the difference between 450 and 650 is just a matter of studying x number of books or for y hours. It's much more about your ability to thrive in a reasoning-based test, and to get there you should analyze what questions you're frequently missing and why you're frequently missing them.

Thanks,Brian! Your inputs are really insightful!