Can't be much worse than freelance writing. It's far and away the most popular writing field.
Oooo... that. Is. True.
Well, as someone who hires creatives for my business and as a creative myself (sort of), my advice is like the ones already given in this thread:
1. I don't care where you went to school.
2. I want to see your portfolio and it must be filled with impressive things. I don't care how you learned it. As a creative I agree that you can learn all this on your own, but sometimes I wish I learned things in a more structured, classical way. Would have eliminated a lot of time doing trial and error and figuring things out on my own. Sometimes I just want someone to tell me how it's done, and I'm confident in my talent to be able to easily understand and repeat it.
3. Price yourself at a level that people can afford. Be prepared to do a lot of free work in the beginning to build up a portfolio and to hone your skills.
4. Take an entrepreneurship course so you understand how business works. At the end of the day, as a business owner I will be hiring creatives for a business purpose, and it is great to have people on board who can share my understanding. As a creative, knowing the business side of things, especially selling, marketing, and how you can contribute to a client's bottom line, is critical to getting clients and getting paid. You make money for your clients and you'll get paid. Simple as that. The more money you can make for a client, the higher chance they will pay you more and see you as valuable to the team. To do this you must have an understanding of and respect for business.