Hi mtvmtv,
To start, a 610 is a strong initial CAT score (the average score on the Official GMAT hovers around 550 most years). In addition, many GMATers spend 3 months (or more) of consistent study time before they hit their 'peak' scores, so you've given yourself plenty of time to study - which is also good. To consistently score at the 720+ level, you will have to hone some specific Quant and Verbal skills though (and as an aside, approaching any GMAT question by doing work "in your head" is NOT a good idea - as doing that greatly increases your chances of making a silly mistake - so you should look to change that 'bad habit' as you're training for the Quant section going forward).
Before I can offer you any additional advice for your studies, it would help if you could provide a bit more information on how you've been studying and your goals:
1) How long have you studied so far? How many hours do you typically study each week?
2) What study materials do you currently have access to?
3) Are you planning to take the At-home GMAT or are you planning to take your GMAT at a Test Facility?
GMAT assassins aren't born, they're made,
Rich