Take classes that work out your brain.
I am a believer that a good student has a balance of both technical and conceptual skills. That being said, you can never have enough classes that explore editorial and conceptual concepts. It doesn't matter if you want to do comic books, animation, or art for galleries- train yourself to have good ideas and be a problem-solver. Not only will you be a better artist, but you'll be smarter when it comes to other areas of your business- marketing, unique self-promotions, and being able to find opportunities where others don't. At my last corporate job, I realized my editorial illustration background gave me a knack for writing copy and thinking of marketing ideas, which propelled me into another area of the company and was a lot of fun. Not only did I learn a lot from those experiences, but it made me valuable as an employee with multiple skills.
Learn from good teachers, no matter what they teach.
Probably some of the most sound advice I got in college was to not focus on class titles when picking my courses, but rather who was teaching them. There were a bunch of amazing teachers that students flocked to, and you wanted to sponge up their knowledge as much as possible. Maybe they were teaching watercolor techniques, or maybe it was a class focusing on poster design. In the end, find out who the great teachers are in your department and try to have at least one class with each of them.
College is the time to experiment. Step out of your comfort zone.
One of the biggest mistakes you can make is to start a curriculum with a big fat label on yourself: Children's Book Illustrator. Fine Artist. Graphic Designer. Putting yourself in a box will make you miss out on classes that could help you in some way, even if it's not obvious (for instance, you could take a landscape painting class that revolutionizes the way you think about color, which influences your graphic design work). You will have a main focus in your studies, no doubt, but don't put the blinders on and ignore classes that could enrich your skills. Film majors should take print making classes. Illustrators should learn about industrial design. This in a way goes back to the idea of Style Soup, which I have discussed earlier. Remember, The only label you should be wearing during your education is Student.