Classes? Well, the reality of what is required depends a lot of the country you are going to work and its specific rules. There are 3/4 year degrees in interior design and sometimes 1 year courses more targeted for people who have previous education or experience on it. But the truth is that you’ll need proper education no matter where you’ll work (today is harder to get away with just “good eye”, some well known designers did it because they started a long time ago or they are not designers but decorators) and on top of that you may have to pass some exams made specifically to assess interior designers capability of working so clients have guarantees of quality.
It’s not rocket science but it’s demanding in terms of the scope of things you should learn. I tend to see an interior designer more like a project manager, because you won’t be able to implement your creative ideas unless you know how to organize and prioritize the whole process and project.
*I added this comment (thank you^_^) because it really focus on what I wrote above:
agreenseason said: It’s much easier to become a “stylist” or “decorator” without a degree if you just have the eye for that. As a commercial designer - which is what I do - you need a design degree, a few years of experience, and you NDICQ.