Read the Texas Essential Knowledge and Skills for the subject area in which you want to be certified so that you have a better understanding of what you will be expected to know. Go to the Texas Education Agency, or TEA, website to find these.
Download a study manual from the State Board for Educator Certification website. There are many to choose from as each corresponds to a specific version of the TExES test. Look through the options and pick the one that applies to the specific subject or grade level in which you are seeking certification.
Look through the domains, or subjects, that the test will cover and identify which ones are covered the most on the test and which ones you know the least about. The manual you downloaded will tell you how many questions from each domain are on the test and this will give you an idea of which subjects are most important. Make note of any domains that you feel uncomfortable with so that you can spend extra time studying those topics.
Review the material covered on the test by reading through the study manual or other reputable books on the topic and referring to notes and materials from any education classes you have taken.
Answer the multiple choice practice questions that are included in the study manual. Identify the domain of each question you missed and look for patterns of subject areas you had trouble with.
Make flash cards with quick facts or key terms from each domain in which you missed questions. Go through the flash cards until you establish good recall for each item. Remembering them will help you weed out incorrect answer choices and inevitably get more test questions correct.
Take another practice test and assess your improvement. Repeat the flash card process for any areas that you still had trouble with.
Sign up for a TExES preparation class at the education service center in your area. There are 20 regional education service centers in Texas and their locations and contact information can be found on the TEA website.