Signing up for the military involves finding out what you are good at, and then trying to find a job or career specialty that will fit what you are interested in. In the modern military the job that you have is linked to how well you do when you take the Armed Forces Vocational Aptitude Battery. This is the single most important test that a person will take dealing with military enlistment, and it features different elements to judge your aptitudes and talents. This is known as the ASVAB test, and it helps the military figure out where it will best use your talents. The thing about the ASVAB is that you can have a definite measure of control over your life in the military if you do well on elements of the ASVAB that match your interests.
Many people think that you join the military and you sign a contract, and simply go off to boot camp, without any more to it. But there is more involved than that. In the military, in modern times the job that you get is linked to the test, each part of the ASVAB test has a relationship to the military specialty that you will have or be allowed to enter. The better that you do on the test especially on certain portions, then the more choice you will enjoy on what type of job you do. If for no other reason than that it is important and considered wise to study and prepare carefully before you take the ASVAB test. There are minimum scores that you must achieve in order to enlist, and also minimum scores on some portions. For example for some jobs that require a lot of expertise in electronics or mathematics then you have to have a certain score on one area, while to be able to go into a job that takes mechanical knowledge you may have to score higher on a different part of the test.
The ASVAB has several different sections, and skill testing in areas such as math, science, vocabulary and general knowledge, as well as other areas of the test. So, go online and find some study and practice tests, there are several practice tests online that will assist you in your efforts.