I know exactly where you are coming from as my scores after studying for a long time were not that great either.
I'm studying to take the GMAT again in November (wish me luck) and I have found the Manhattan series of books (Quant and Verbal) extremely helpful. They help lay a foundation in both sections that will serve you well in your preparations. I think those along with the OG12
should help you get closer to your goal.Posted from my mobile device