As enigma pointed out right, no matter how many rules you learn, at the end of the day it is your practice that comes to the rescue. This is applicable to all categories unless your brain is like a super computer: you feed once, it stays there.
In fact GMAT recognizes these 'super computers' as well, and hence no question is straight forward. So, the only option is practice.
And from my experience, I would suggest practice everything: if you practice quant for some days, and comes back to it again after spending some time on verbal, chances are that you would have forgotten what you have learnt (at least this happens with me
Hence once you get to know basic rules, allot time to each of the categories so that you stay with all.