Hi quentinv1,
Many GMATers are unhappy with their initial practice scores, but you really shouldn't be. That 300 is just a measure of your skills right now - and you'll improve on that result over time as you learn more about the content, Tactics and little 'secrets' of the Exam. It's also worth noting that if you finished both the Quant and Verbal sections 15 minutes EARLY, then you likely 'rushed' through a bunch of questions (and made little mistakes) that cost you a lot of points. You likely have the ability to score higher right now, but you will have to focus on learning and practicing some specific Quant and Verbal Tactics before you can consistently score 680+. Thankfully, the GMAT is a consistent, predictable Exam, so you CAN train to score at a higher level - and you could potentially improve a great deal over the next 4 months.
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 how you've been studying and your goals:
1) How long have you studied so far? How many hours do you typically study each week?
2) What study materials do you currently have access to?
3) When are you planning to apply to Business School and what Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich