The analytical writing section, which consists of one essay that analyzes an argument, is the first thing you will see on the test. You will be provided with a prompt and then given thirty minutes to read it and write an essay analyzing the effectiveness of the argument. This section tests how well you can logically analyze and argument and how well you can persuasively write.
You are scored on a scale from 0-6, in half point increments. Your essay will be scored by two separate entities, one of which may be a computer program. The two scores will then be averaged. If they are different by more than a point, then a third reader will determine the score.
MBA admissions committees just want to know that you are capable of logically analyzing an argument and creating a persuasive response. Thus, an amazing AWA score won’t wow them into accepting you. However a very poor score (4 or below) may send a red flag. The best way to study is to get the official GMAT Write software from GMAC, or through a course, many of them provide it. If you score a 4.5 or higher on both, then I would say you are done with studying for the AWA. However, if you struggle with writing and end up scoring lower, you might want to do some additional practice.