If you intend to attend graduate school in a Business or Management-related field, most schools require the GMAT. The good news is that the makers of the GMAT provide wonderful online resources to aid in preparation. So I do not need to tell you much more than GO to that website! But of course, I will add a few tips of my own.
Step one: Start early. Set aside regular review sessions for at least a month before you take the test, longer if you are uneasy with standardized tests. My advice is to schedule 30-45 minute time slots every day or so--do not wait for a longer amount of time to study. You will be more likely to make progress if you can put in shorter sessions more often.
Step two: Go to http://www.mba.com/us
Familiarize yourself with the information and videos, particularly under sections titled "Information about the GMAT" and "Preparing for the GMAT."
Step three: Download the free GMAT preparation software. I must emphasize how helpful it is to study practice questions provided by the company that creates the test.
My advice is to work through the problems, one-by-one, untimed. Look up the answers right away. If you get a question wrong, study to make sense of why the right answer is the right answer. If you aren't sure, you can often google for more information, even the occasional youtube video, that may help you make sense of it.
Step four: If you feel you need more support than this individual review, a few resources may help:
1. The Writing Center www.writingcenter.appstate.edu
They can provide feedback on practice essays and sentence corrections.
2. The drop-in math lab. Find out more here.
The above services are free to Appalachian students. You may also find it helpful to create a study group with others who plan to take this test or to ask professors or other students to find out what approach to reviewing helped them the most. You also should find out what score you need to be competitive on the test. That may give you a sense of how much effort will be needed to do well.