In order to enlist you must be tested. If you pass the test your in. The test is up to your recruiter. If your considered good enough you'll also be given a rank... if not... well your a maggot and considered in "boot camp". You will be trained untill otherwise dubbed "private". If your out of boot camp and would still like to improve you may challenge for rank. If you somehow manage to get the attention of one of the Leaders or Generals you might get special training.
Otherwise...SUCK IT UP AND FIGHT!