Hi Dunkirk,
A 650 is a really strong "cold" score on the Official GMAT. You're clearly a strong critical thinker, so it likely won't be too difficult to hone your skills and hit 700+. There are also a variety of different ways that you can study for the GMAT - and you've given yourself plenty of time to study, which is good. Before I can offer you the specific advice that you’re looking for, it would help if you could provide a bit more information on your timeline and goals:
1) When are you planning to apply to Business School?
2) What Schools are you planning to apply to?
3) Going forward, how many hours do you think you can consistently study each week?
GMAT assassins aren't born, they're made,
Rich