Look at the first test you took. Identify which sections of the exam that you did not perform well. These are the sections you should focus on. Another option is to take the self-assessment modules on the Test Prep Review website to find out in what areas you are weak. The four areas to focus on if you want to get a qualifying score on the ASVAB to enlist are arithmetic reasoning, word knowledge, paragraph comprehension and mathematics knowledge. If you want to improve your chances of getting an enlistment bonus and the occupation you want, focus on other areas of the exam.
Go to the public library and pick up a copy of "ASVAB for Dummies," by Jennifer Lawler and Rod Powers. Other books to try are "ASVAB Success" by LearningExpress Editors and "ASVAB (CliffsTestPrep)" by Fred N. Grayson. These books focus on specific areas of the exam and provide tips for improving your score. They might also include a practice exam. Read and work through the sections that you need to improve. Work through the links in the areas in which you need to improve on the Test Prep Review website as well.
Take practice exams online. They provide the correct answers when you are finished so you can get an even more specific idea of the types of questions you need to work on and how to answer them. Military.com and 4Tests.com are two sites that offer free online practice exams. Take a few minutes and study the answers you missed.
Arrive to your next test well-rested and having eaten breakfast. Take some water with you to help you stay hydrated during the exam. Spend more time answering questions in the areas you worked on, but do not neglect the other sections of the exam. Answer all of the questions on the test. If you are not sure of an answer, leave it, but come back to it to answer it. You are not penalized for incorrect answers on the ASVAB.