Royally screwed up! 1st time: 630, 2nd time: 480!!!

I hate when girls pull out the cry card, it works every time.

Anyway, on a more serious note, that kind of fluctuation in just a month probably means you don't have your fundamentals in place. And that change was much more pronounced in your Quant score.

I think you really need to sit down with a GMAT guide and go through it slowly to understand the nature of the questions being asked.

For Quant, it is probably much harder (but no more time consuming!) than Verbal, but it can be done. Don't think that just doing lots of practice questions will do the trick, you need to study the basics and do exercises to solidify your math skills. When you truly understand the basics, I am 100% sure that you will see a huge increase your math scores to the 90+ %iles. That's the thing about Quant, you don't need to know a lot, you just need to really know the basics.

For Verbal, isolate what kinds of questions your doing well/poorly on. Of the three types, SC, RC, and CR, people tend to have more trouble one some than others. Try to figure out which of them you need to improve on, and again learn the fundamentals.

The GMAT is all about learning the fundamentals really down pact. Once you do that, use sample questions to solidify your learning and identify where you can further improve yourself.

Hope this helps,
J