Hi Amoner,
You seem to understand that some aspects of your studies have been ineffective so far. That is an important step to ultimately finding the resources that will help you to improve and making the necessary adjustments to how you study. Before I can offer any advice, I'd like to know a bit more about how you've studied so far:
1) How long have you studied?
2) What materials have you used?
3) How have you scored on each of your practice CATs (including the Quant and Verbal Scaled Scores)?
Since it's too late to reschedule your current Test Date, you should plan to learn everything that you can about THAT experience (since you'll be going through it again). There are always a number of 'factors' on Test Day that are tough to simulate unless you already know what they are. By taking this GMAT, you should be able to use your new knowledge of Test Day to better prepare for your next attempt.
GMAT assassins aren't born, they're made,
Rich