Hey o,
I've taken the GMAT twice and quant my weakness at first. My first attempt was 700, with a 95th percentile in verbal and 66th in quant. I knew I could do better, so I pinpointed the types of quant probs that were hurting me (ratios, probability...) and studied up on them. Also, the challenges on GMAT club are great for building your quant.
All said, I took it a second time and my quant jumped to 85th percentile... Unfortunately, i forgot to stay refreshed on my verbal and it dipped to 89th, so i ended with a 710. that being said, i'm happy with my score and the fact that i'm balanced between the two areas.
OK. that's all my rambling.... Do some challenges and pinpoint the problem types that are giving you a hard time.
You'll get it done in no time!