What would be the smartest choice(s) to make (military)?

In 14 days I leave for basic training in Ft Leonardwood and will then go to Sam Houston for my AIT(68W). I understand a pretty good amount about green to gold and OCS but out of the two, which would be the better option? I am active duty Army, and when i receive my duty station, i plan to buy a Macbook and finish online college courses in my spare time or whenever, as far as transitioning from the army as a combat medic,to a Physician Assistant, any preferable majors?courses?anything? and finally, any duty station reccomendations? i'm almost positive i can pick my 3 top preferable choices. i'm18 years old as well, just to give an idea of where i'll be after years of college and all that. i'm just trying to gain as much knowledge about the army, and the smartest choices to make as far as transitioning in to a nice career. If anyone also has more in depth information on the thrift savings plan, that'd be great. any other useful tips & information anyone has, i'd greatly appreciate it. thanks.