Most advice from working professional artists seems to be pretty straightforward, and you’ll hear a version of it from most people you ask: work hard, draw like your hand’s on fire, study anatomy and draw from real life as well as from your imagination, etc. But as far as helping you tailor your studies to aim for a job at Cartoon Network or another animation studio, well, there’s a lot of factors involved. Skill is one piece of the puzzle; another HUGE piece is luck, and so is community - the people you forge connections with on your way up.
On Regular Show there seems to be two paths our boarders have taken to get the positions they have. Some of us went to art school for animation, did student films, maybe worked on other shows first as a cleanup artist or intern. Then there’s the rest of us who, by and large, taught ourselves to write and draw and keep to a schedule via the medium of comics. It’s still unusual in this industry to “come in through the back door” (so to speak) and get a boarding gig on an Emmy-winning show without previous boarding experience (as I did), but the 15-plus years I spent studying the finer points of comics-making - pacing, composition, gesture and facial expression, rich backgrounds and hidden details, and above all else SOLID WRITING and COMPLEX CHARACTER DEVELOPMENT - got me this job. And plenty of my co-workers who are a decade younger than I am didn’t even have to put in that time in another field - they were already working competently and had the skills and particular sense of humor RS needed when they got hired.
I’ve glanced over a few of the storyboard tests of people who tried out for the job and weren’t hired. There are some PHENOMENAL artists in the bunch. But RS, and Adventure Time, and Steven Universe all require boarders who can also write, to shape the dialogue and enrich the characters, creating emotionally honest moments and ridiculous pratfalls alike. If this is the career you want, don’t just stick with your animation classes - study storytelling, story structure, classic and modern literature. Study joke telling. Read books from authors from other cultures, translated from other languages (or study other languages if you can!) to expose yourself to different narrative styles. Go deep and critical with the works you love: pick them apart, try to dissect why they affect you the way they do. Try writing in a genre you’re not as familiar with. Build worlds.
Finally, be nice to the people you meet in the field. Ask a lot of questions and avoid demanding anything. Build a solid professional reputation, and your chances of having a favor passed back to you will greatly increase. ;)