Ask for study materials. Teachers do not always provide them automatically, so you may need to request them. All Texas schools are required to help you prepare for the test, as it is a state mandated examination. You will most likely be given a practice test (sometimes referred to as a benchmark).
Go over the material. If you have been given a practice test, take it and ask your math instructor to grade it. Ask for assistance on every problem you have missed, and even questions that you answered correctly but without confidence. Examining the kinds of questions you missed will help you understand which areas of mathematics you need to work on.
Work on material you do not fully understand. Your math instructor should be able to help you out here. Schedule tutorials with your teacher---if he is not available at times that suit your needs, ask if he can refer you to any other faculty members. If you prefer independent study, look over the sections of your math book that pertain to what you need to learn. Most Texas mathematics textbooks are written in a way that the student can self-teach.
Go to bed early the night before the exam. Drink plenty of fluids and be sure to eat a healthy breakfast. Your performance can vary greatly depending on your energy level.