GMAT Strategy

Hi everybody,

I want to take the GMAT beginning of November (not sure about the exact date yet).
I need to score a 550 but if I´m doing this pain in the **** test of course I´d like to do better, maybe around 600-650. Hopefully two month of studying will be enough.

My problem is not the verbal part. I have been through the Manhattan books already and did the OG questions without much difficulty. Critical Reasoning is giving me a hard time but I think I will manage with more practice.

What is really worrying me is the Quant part. I suck at it. Especially DS. I am not dumb (at least I managed my A-levels and my Bachelor Degree with very good results) but I can´t wrap my head around it.
I even don´t know how to best beginn my studies and where to start.

Do you have any advice how I can structure my study plan for Quant? I heard the Geometry doesn´t appear that often on the GMAT, so maybe I shouldn´t focus too much on that in order to save time for more "important" stuff?
Any tipps or advice is appreciated!

Thanks a lot! I will try this study plan. But I still have my 12th Edition of the Offcial Guide. Do you think it is necessary to purchase the 13th Edition as well?