This is an apprentice business. There are no classes, there is no certification. The best way to learn to do it is by doing it, and pretty much the only way you are going to get to do that is by interning/working for an existing agency. Generally for free.
Best case scenario, even if you join an awesome agency, build up an amazing list of clients and start selling right away, it is extremely unlikely that you will be able to earn enough consistent money to live properly until your books are published, earn out and start earning royalties - in other words, for about 5 years.
Is it any wonder that publishing remains a very insular, homogeneous business when to get a job as an agent, who are essentially the gatekeepers for what gets published, you have to agree to work for no- or low-pay for up to five years? There are not many people who can do that outside of those who either come from a family with money or have spousal support. This makes me think that there's not alot of diversity of life experiences at the literary agent level and as a result, not alot of diversity of viewpoints being represented, with a few exceptions.
I would not be surprised to find out that literary agents are overwhelmingly female, white, and from upper middle class backgrounds. And I can't help but wonder if the reading public would be better served if the demographics of this occupation better resembled the demographics of its audience. And even if you can argue that upper class white women are the biggest consumers of books in this country, how much of that is a function of the literary landscape already catering to their interests and life experiences?
This was why I was thrilled to find this interview with agent Elizabeth Jote:
What challenges have you faced in general and any challenges in being a person of color?
In this industry you’ll find a serious amount of Ivy Leaguers, which stems from its aristocratic origins... It was a miracle that I even found out about publishing as an alternative career path to going to Law School . No one was showing up at Hunter College saying, “Hey, you ever thought of this?”
What ways do you see would be effective in getting more Asian/Latino/Hispanic/Native American/African American males and females from all socio-economic levels to pursue careers as literary agents?
(Note: As an aspiring writer currently seeking representation, I would be thrilled to have any agent. This post is simply my observation of this world, as an outsider and newbie.)