Only one word, practice! The GMAT is a test and like all tests there is a way to take it. That includes getting comfortable with the exam format, taking sample exam under test taking conditions, brushing up on basic numerical and verbal techniques and concepts that may have turned rusty since your departure from college and showing up on the test date with the right mindset. You do all of the above and cracking the GMAT 700 barrier is a question of time. Compared to a decade ago when Princeton review and Kaplan forums were the only sources of solace for exam takers, today you have enormous data and prep material available online. Just make sure that like the rest of your application, you start practicing early. Don’t leave it too late.
As an international student and a non-native speaker of the English language, the rule is that you are at a slight disadvantage. But that is not always true. If you are good with numbers and have been reading actively on a regular basis, you won’t have an issue with the exam. But if you hate numbers and don’t read aggressively, there is a chance that the exam and GMAT exam prep will psyche you out. But remember that if I can break the 5 minute a mile barrier with a year of training and running, you can beat the 700 barrier in GMAT with practice and the right mindset.