A reader posts: "I am interested in pursuing a Ph.D. However, I am terrified of the math portion of the GRE. Is a test prep class necessary?"
There is no one way to study for a standardized test like the Graduate Record Exam - it depends on several factors: the student's skill, needs, ability to work independently, and motivation. Your first step is to take a practice exam on your own, using either one from a book or one published online. How did you do? Look at the pattern of your scores. Are most of your errors similar? Are there clear content areas in which you need to improve? Or did you make some errors in many areas or many errors across the range of topics? Sometimes a student's pattern of errors shows distinct areas in need of improvement. In these cases it may make sense to study on your own, retake practice exams, and see if you improve. If you don't, then seek tutoring and try again. If your scores remain low, consider taking a course. Students who are particularly unskilled or who have greater needs for assistance, such as those who score poorly on self administered practice exams, should study but also seriously consider taking a prep course in order to raise their scores. GRE scores are not only the ticket in to graduate school, but an important factor in whether you receive funding for your studies. Not everyone needs to take a GRE prep course, but if your scores are low or you scores do not improve regardless of your own studying, a prep course may be for you.

Comments
A lot depends on the field you want to get a PhD in. It is my experience that many great universities don’t even require the GRE and if they do, they only want the subject test. If you are planning on a degree in the Humanities, likely they won’t give a hoot what your math score was. You would not be taking any math courses at that level and your English score would be all they care about.
I got a great math text that goes from pre-algebra to algebra, geometry and some statistics and refreshed myself on math step-by-step only to find out no one at grad school cared at all about my math score!