GMAT Strategy

So I attempted one of the GmatPrep practice exams, after only spending a few hours reviewing basic math. Needless to say the experience was a huge eye opener towards the amount of studying I need to put in for this exam. I bombed and did not even break 500.

My background is an undergrad in Finance and currently working in accounting for a large fortune 500 company. Sadly my score is embarshing and I felt sick and almost vomitted when I finished the preactice exam and seen my score.

I have the OG11, Cliffs math review, as well as other highly suggested material from this forum. I plan to dedicate a month or so to studying this material and re-learning my basics for standardized exams before attempting another preactice exam.

I'm still shocked and feeling inadequit based on the practice exam. I took the exam when I was a bit aggetated at the noisiness of the library, yet besides that I still had a blank memory when taking the exam. I did not feel confident in any of my answers and guessed a lot. I had not one question were I remembered the formula and confidently and quickly worked the problem.

All the verbal questions seemed like each answer could be correct and the quant section was like reading chinese.

How much can one improve from studing OG11 to improve from unstudied to well prepared.

Thanks