Evaluate your reason for taking the test. Usually, you have applied for a position as part of a project or to become a new employee. Read the job description and ask yourself whether the position is more communications- or calculations-based because this will help you determine the kinds of questions you will be asked.
Find out the particular test you will be taking and ask for study guides or materials. Depending on the project or position, the FAS test will be different. For example, Army linguistic managers need to take the FAS defense language proficiency test. This is a more communications-based position, as opposed to something like an engineer, which is more calculations-based, so the test will be more likely to ask you about symbols, codes and meanings.
Study your materials thoroughly and set aside time each day to look over the material. Aptitude tests often have more than 100 questions that must be answered in time spans as short as 20 minutes. You want to answer the questions accurately and quickly.
Study by yourself initially. Friends and study partners can be distracting in the beginning, so review the material for a while on your own and then ask a friend or colleague to help you by randomly quizzing you on the material. This will also help you improve your speed.
Break up the study time over several days. The more time you have to prepare, the better. Avoid cramming for the test so that you remain clear-headed and in control. Cramming often causes you to forget short-term memory information during the test, and it often means sleep deprivation and an increased sense of nervousness.
Focus on your weak areas after several days of studying. If, for example, you are taking the FAS military linguistics aptitude test and you find you have difficulty with a certain language or with certain codes, return to these for further study and try some alternative methods like flash cards and mnemonic devices.
Find out from the testing center or examiner how the tests will be scored. If you receive negative marks for wrong answers it is best not to guess, but if there is no penalty fill in every answer.