as far as enlistment and education, i know that the army (can't speak for the other branches) takes the ASVAB score and your grades (high school/college) to figure out what jobs you are mentally suited for. when i went in back in '96, every job in the army was available to me. i chose combat engineer. later, i re-classed (changed my job) to satellite communications. i got a hands on education and got paid to learn it. if you are a twit and get a crappy job in the military, chances are you'd prolly get a crappy job outside of the military. job selection isn't about just "we need people to shoot at the enemy". the smarter you are, the better your options. and the more you milk your options inside, the better off you are outside.