[DF Filter]
Well, to become one you need an advanced education in Behavioral or Forensic Science, as well as at least three years experience as an FBI special agent. [Never mind that he got special treatment.]
As for what we do... we look at victimology, behavioral patterns, physical evidence and any other clues we can find on a crime scene and from that we extract a profile of our UnSub. That's Unknown Subject, the suspect or suspects in the investigation.