Here is how I got to 670:
I meant to this earlier but I wanted to wait till I hear back from the B-schools. I now have admits from both Kellogg and Booth Weekend programs. So, time for a post.
Crowan Roberts- Crowan is a GMAT tutor based in the California bay area. I gave the GMAT 3 times last year and twice I score 590, so you can imagine my frustration. I tried everything possible under the sun to take the score higher but nothing seemed to work. I realized that a mindset change was needed to break into the GMAT. A friend recommended me to Crowan. Crowan did the job and changed my mindset towards the GMAT. He has the best strategy for Math and it really works! I scored 49 which was the highest I have received so far. He also improved my strategy towards SC which was my weakest section in Verbal. He calls himself the "GMAT Guru" and he truly keeps up to this title

GMAT Club Math and Verbal Tests- I gave around 15 of the Math tests and I think they played a big role in the 49 score.
Aristotle SC guide: I found about this eBook on GMAT club and this is the best SC guide out there. It's a great read! I had tried Manhattan and a bunch of other books but Aristotle rocks!
GMAT prep exams: Do give the Prep exams. I have listed my progression over time.
GMAT Prep 1: 640 (1st attempt)
GMAT Prep 2: 660 (1st attempt)
GMAT: 590
GMAT Prep 1: 700 (2nd attempt)
GMAT Prep 2: 740 (2nd attempt)
GMAT: 670!!! Done

Ear plugs, Felt pen, Manhattan test booklet- A minor thing but I practiced big time using ear plugs to keep the environment the same for the actual GMAT. The same holds true for the pen and test booklet.
AKB