GMAT Strategy

Hi forum, this is my first post here so please be gentle! I've been preparing for the GMAT for around a week only now - mainly by running through the Manhattan GMAT books. I've taken the free MGMAT CAT and have scored (for me) a disappointing 630 (I'm aiming for low 700s-750 and would want to take the GMAT a month or so from now).

What I've been able to figure out through this week of prep is that my key weak areas are -

• Probability & Combinatorics, Coordinate Geometry and Inequalities on Math - and as a broad topic - Data Sufficiency

• Critical Reasoning on Verbal

I was wondering if people could recommend some resources that are specific to these areas for me to work on - and especially for Data Sufficiency. I wish MGMAT had a book that was focused just on DS instead of having it at tagged on at the end of the Quant books. In terms of resources - I have the OG12, a in-transit Powerscore CR (and the Manhattan GMAT bookset)

Finally, I'm kind of preparing on my own - have not joined a class (online or offline), so are there any GMAT prep calendars (I know of the BTG 60-day studyplan - is there something similar for 30 days?) Thanks for any help you can provide and your patience in reading through my query.