Qualifications
There's no one-way "career track" to becoming a sports agent; it's not like becoming a doctor (college > medical school > internship > residency > now you start working off your loans) or even a….limnologist. Many times, it's about being armed with the right information and having the right skills while being in the right place at the right time.
Studying business management, math, and communications at a university isn't a bad idea; as a sports agent, you'll be dealing with statistics, variables, averages, and the like. And you'll be dealing with people's lives, money, and families, so hey, maybe a minor in psychology isn't a bad idea either.
There are sports agents (more than you'd think) who have law degrees, too; yes, you read that right. In fact, it isn't an uncommon thing. Again, when you're doing tricky, big-money negotiations for a once-in-a-generation athlete whose got a surly attitude, presenting her in the best light for the stakeholders and convincing them that they're on the winning end takes a lawyer's, uh…panache.
On the other hand—send your folks out of the room—to be a sports agent does not require a college degree. (Caveat: This isn't true for all types of sports agents; for example, the NFL requires a post-graduate degree, be it a master's or a law degree in order to be a player representative.)
But (and yes, Mom and Dad can come back in) it'd behoove you to at least get a bachelor's degree in at least one of those areas. Then there's that possible law degree and even a master's in business management or sports management. This is a job that takes smarts—the book kind and the street kind (the kind that only comes from experience).
Most states always require some sort of certification, and all states require it if you're representing an athlete in the NFL, NHL, MLB, or NBA (source). Same goes for agents wanting to begin to represent student athletes, which makes sense. People can take advantage of young, talented athletes (imagine that).
But again, there's no straight line to this job; it all depends on your personality, your experience, your interests, and where you are and when.
And remember that part about glory in this career? A good sense of fairness and professional and personal ethics will keep you on the straight and narrow track to success.