Obtain a preparation manual for your test subject by visiting texes.ets.org and clicking on "Preparation Materials" in the menu choice. This manual breaks down the information the test covers and the kind of knowledge you will need to take the test. Review the test format. All TExES subject exams have multiple-choice questions, but some may also require you to write out an explanation of concepts, theories and processes in a clear manner.
Review every knowledge area and decide where you have strengths and where you have weaknesses. Focus on your weakest areas first, and obtain reference materials to help improve your knowledge. Give yourself twice the study time for these areas, but make sure you also review your areas of strength to ensure correct answers on test day.
Design a study program that gives you enough time so you will not have to cram as the test approaches. Select a test date and establish your study sessions backward from that date so that you are fully prepared two weeks before the test.
Review your reference materials and the study guides provided in the preparation manuals. Answer the practice test questions in the preparation manual. If you are taking a subject test that includes written-response questions, review key concepts and theories in your field and practice writing an essay that explains them in your own words. These questions are designed to assess how well you communicate knowledge to your students.
Review the answers to your practice questions and make note of the areas in which you did poorly. Concentrate on shoring up these areas by testing yourself frequently on these questions and allowing yourself extra study time to ensure you have a firm grasp of the material.