How should I get a job working for the FBI or CIA?

Alright well im about to head off to college in August and i am not sure what I want to do but I do know that I really want to work for a Government agency. I am playing college football at a division two or division I-AA school(I have received offers from Gannon, Duquense, Robert Morris, Central Arkansas, Elon, and Villanova, i just have yet to accept any or verbally commit). I am unsure of what major I want because I am unsure of which would be the best and I am highly considering doing ROTC but I am nervous about the four years in the Army afterwords. So basically im asking what major would be the best and is ROTC or any Military career necessary?