Here are some things to consider before you register for the exam.
Begin by reading the ETS Preparation Materials, including their Study Guide Companion. After working through the small set of sample problems, you should have an idea about which topics you will need to work on. If so, seek resources such as Kahn Academy and notes from relevant courses to improve your knowledge in these areas. You also can reach out to math department members and the Math Clinic for help with specific topics. There may be restrictions imposed on the number of attempts you are allowed. Therefore,you will need to carefully prepare for this exam prior to taking it.