Do not sign any papers until you take them home for a parent, teacher, or someone else whom you know and trust to review. You have every right to request time to read the paperwork before signing. If a recruiter is pressuring you to sign without reading everything carefully, they are not looking out for your best interests. Check out Sgt. Abe—the Honest Recruiter for a detailed description of the enlistment contract.
Make sure to get all the recruiter's promises in writing in your enlistment agreement. Spoken promises will not protect you.
Find out whether you need to pass a special test, get a security clearance, or do anything else before you can get the job or options that you want.
Make sure you keep a complete copy of everything you sign. Don't rely on a recruiter's promise to provide you a copy at a later date.