The FBI hires about 500-800 people a year, they get about 10,000 applicants for those jobs so the basic odds are worse than 1 in 12 to 1 in 15. You have to be able to really stand out.
My uncle was a top person in the FBI lab, his son also became a special agent, this was their career path. Uncle> 3 yrs college, WWII Navel Officer, finish college on GI bill and goes on to get a PhD in Chemistry then joins the FBI as what amounts to the the original CSI team and he came up with several ways of using chemistry to solve crimes. His son> U of Maryland, (PolySci, Football scholarship, honor role, ROTC), two tours in Viet Nam as an officer, 10 years Montgomery Country (suburban DC) Sheriffs Department (7 as an deep undercover narcotics agent) during which he got a law degree from Georgetown. He joined (somewhat reluctantly) the FBI largely because his success as an undercover agent added up to a lot of people who really, really wanted to kill him, and being killers, they would have eventually succeed. He often joked that he joined as a witness protection program for cops.
Military experience is important for two reasons. One, they know that you know what military discipline is, and most police operations are built on a military rank/file system and expect military discipline. Two, federal law demands that veterans are given preference in all jobs from being a janitor to the job of being director of the FBI.
For a long time - though this has toned down of late - the FBI was the most Catholic of the federal police departments and lots of their people came with undergrad degrees from Georgetown, BC, and Fordham - often called 'the Catholic Ivy League.'
Of course West Point and Annapolis are also pretty good. The class rings from those two schools are golden in DC.
But the importance of the colleges is a very real deal. First because it's true, second because the person sitting across from you went to one of them and thinks (knows) they are superior to say Idaho State College, and third, because those organizations have special relationships with certain schools and professors who track the superior students and direct them to the internships and 'the right people.' Like the guy in the office next to me who had a 'special' relationship with the CIA and just about every year sent his best student to work for them. The 'old boys network' is a very real deal.* What you know is critical, but who you know gets you in the door, gets you talking to 'the right guy' and all that.
East coast colleges also are closer and it's a lot easier to intern and take advantage of those kinds of opportunistic than if you were at UCLA.
You should have a 'path of excellence' reaching back to HS, honor roll, inter-mural athletics, extra-circular responsibilities.
There is also an organization culture thing (of which the FBI has a long-developed one) of wanting - not 'trained' people, but 'trainable' people. They want, 'smart putty' as a friend of mine puts it (and I like that), someone who has the capacity to be molded, but doesn't have a real 'shape' as of yet. The FBI Academy is set up to take lawyers and accountants (that whole Al Capone conviction was not lost on them) and make FBI agents out of them, it's not set up to take criminal justice majors and make lawyers and accounts out of them. I've often talked with people in my current profession about getting people to train that really don't have any theater experience, but are trained carpenters, mechanics, and technicians and make theater people out of them. In other words, we don't want to have to re-train the bad habits someone else built into them out of them.
In a lot of places there is a right way, a wrong way, and our way. It's often preferred that you learn only our way. My cousin said that his undercover experience often conflicted with the way the FBI wanted it done.
<this is for special agents, there are all sorts of 'clerks' with lower level skills, but I take it that's not what you are thinking of> There are currently five career paths in the FBI, accounting, computer science and information technology, language, law or diversified. For 'law' they don't want crim justice majors, they want JDs with court experience (it's the not-so-secret reason that the FBI conviction rate is in the 90th percentile). It's because the case is put together by experienced lawyers to be air-tight. If you are arrested by the cops in my town it's 50-50 that you will be convicted because they are so sloppy. If you're busted by the FBI, you're going away. And for languages they really don't want people who 'studied' a foreign language in school, they want people who are native speakers, or grew-up bilingual, or learned immersion style. Just knowing the language is not enough, you have to be able to speak it well enough to fool native speakers, and to understand the nuances of the language, and the regional variations. Something that academic study of languages just can't do. It's called 'well-educated native speaker level' - and that basically translates into not only being able to translate, but to to think in that language on a very sophisticated level.
Think of it this way... I can read (slowly) Spanish. I can speak a little, understand a bunch as long as they know I'm a gringo and they go slow. But when my GFs family gets together and they start speaking Mexican Spanish (one of the fastest language in the world) I'm lost by the second word. Moreover, if your cover is that you're from LA, you're Spanish better be LA Mexican Spanish and not that NYC Puerto Rican based Spanish - and any/every native speaker can tell the difference, even if I can't. And that's a life and death difference in undercover work.
Those who succeed are those that know usually. But they are also the ones who know early on, and work hard toward those goals, so you're out ahead there.
* - in the early days of the CIA many of the agents were not only Yale men, but Skull and Bones people at that.
