You enlist making the same money as everyone else in your pay grade. Maybe they will give you one stripe free out of basic, with a pay raise. There are various bonus arrangements, mostly with the Army and Marines. And mostly with the jobs they need to fill. I was in USAF and can vouch for it being a fine organization. Even better, while your friend serves, he can finish his college degree.
Its an honorable life. You just aren't going to get rich doing it. And neither will you ever worry about Medical, Dental, food on the table....ect.