I managed to pull my score from a mere 600 to a fabulous 740 (Q51/V39) with the help of GMAT classes at The Princeton Review. To everyone having doubts about their course, it is hands down the best GMAT prep program out there. The student portal has 10 mock GMAT exams which are actually pretty close to the real exam and the other drills on the portal do help pull up the score. The instructors are of top quality and class room teaching is quite elaborate and crisp (they also provide 4 preparation books). Another thing which I found really helpful was the booster sessions which are provided free of cost but have to be earned. Booster session alone will add 40-50 marks to your score. All in all, I feel they provide a really good deal at a very nominal price, and they results are assured!