So you like books, you have an eye for good writing and that English degree isn't getting any more marketable. Or maybe you've received a bunch of rejections to your query letter and thought, "Oh yeah? Well what qualifies YOU to reject me? Is there literary agency school? Do you even have a law degree?" Nope. Here's what it takes.
First, I'm assuming you live or are moving to New York, (or, more specifically, Brooklyn, Queens or New Jersey, because you won't be able to afford Manhattan!). Yes, I live in San Francisco, but I'm already taking up one of the five or so spots in San Francisco. Sorry about that.
Becoming a literary agent is sort of like becoming a blacksmith. In the olden days you didn't go to blacksmith school, you worked as an apprentice to an established smith for a very long time, learning the trade, getting up early to start the kiln, and fetching the blacksmith's hard tack. Usually the apprentice was only given room and board. And then, one day, when he had learned all the blacksmth could teach, the apprentice could go forth and open his own shop. This is basically how it works with literary agents.
In order to become a literary agent you have to first become an assistant to a literary agent. And actually, in order to become an assistant you often have to first work as a receptionist, as an intern or in the mail room. Believe it or not, there are about 700 applicants for every assistant job. Assistants answer the phones, keep track of contracts and payments, read queries, and fetch their bosses' hard tack I mean coffee. In the process the assistant is actually learning a great deal about the business -- who the important editors are, the terms of publishing contracts, what books work and what don't, how to spot a good project, etc. etc.
After two or three or four or five years as a lowly assistant, if you have proven yourself able, and you haven't bungled too many follow ups, you may be allowed to take on a client. Or two. But no more. And then, a couple of years later, if you have done well with those one or two clients you might be allowed to take on a few more. And so on.
And then you're on your way to fame and glory, right? Well, not so fast. Keep in mind that a young agent is up against a crop of very experienced agents with deep contacts and a polished resume. Being a young agent is a long, hard slog. You have to find diamonds in the rough and read millions of manuscripts and, honestly, have a good deal of luck. But eventually, I'm told, you get there and then all of a sudden you wake up and half of your clients are on the New York Times bestseller list. Or you wake up one day and decide a job at the bakery isn't looking so bad. You know. Either way.
Does this mean that all agents are manifestly incompetent because they did not go to agenting school? Actually, no. As old fashioned as it may be, it's actually a pretty good system. Assuming you work for a reputable literary agency, by the time you are given the go-ahead to take on clients you know a great deal about the business, you have experienced colleagues to draw upon and you've networked relentlessly with your fellow publishing assistants. You really have to prove yourself. If you manage to work your way up to be an agent it shows a certain level of dedication (or insanity).
So if you still wanna be a literary agent, good luck to you! But don't quit your night job.