A good way to get a better handle on what you need to know is pay attention to the ads you see (or hear, or click on). Who do you think they are aimed at? Which ones do you react to most? Why do you think that is?
In addition to English Literature and Journalism classes that directly relate to writing and researching, I recommend that you take at least a couple of business or even IT classes to get a sense of what kind of language and topics you'll likely be working with as a paid copywriter. The more you know about the domain and topic the more effective you'll be as a copywriter and, in my field, copywriters capable of producing IT and tech content are always in high demand.