Hi TheRover34,
To start, a 540 is a solid initial CAT score (the average score on the Official GMAT hovers around 550 most years). That having been said, raising a 540 to the point that you can consistently score 700+ will likely require at least 3 months of consistent, guided study - and you'll have to make significant improvements to how you handle BOTH the Quant and Verbal sections. Thankfully, the GMAT is a consistent, predictable Exam, so you CAN train to score at a higher level.
Since you've admitted that your 'math skills' are a bit rusty, you might want to do some general math practice before you commit to a GMAT Study Plan. For free math practice and help, I recommend that you set up an account at Khan Academy (
www.khanacademy.org). The site is completely free and makes the learning a bit more fun and 'game-like' (as opposed to the dry academic approach taken by most books). While the site is vast, you should limit your studies to basic Arithmetic, Algebra and Geometry. After spending a little time re-building those skills, you can start your GMAT studies.
Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on your timeline and your goals:
1) When you say that you had a few 'technical difficulties' during this 1st CAT, what does that mean exactly? Were you unable to finish all the sections (and leave some questions unanswered?) or are you referring to not knowing how to answer certain questions (but you chose an answer anyway)?
2) What Schools are you planning to apply to?
3) What are the exact application deadlines that you are facing?
GMAT assassins aren't born, they're made,
Rich