Thinking back to when I got into this business in 1990, I would have been SCREWED if I just started my own business back then.
I worked in Graphic Design for printed media from 1980 - 1985, learned computer graphics and basic layout.
I took a break from that for a while, and then took a job with a sign company in sales at first, then started doing some light design work, then some fabricating, then some installing. It was a small shop, so it is very common for everyone to do a little bit of everything. I learned alot while working for someone else. Some of the best things that I learned were what NOT to do.
I finally went out on my own (With my Wife who was also in the sign business) in 1996. Even with our experience, it was tough to be profitable for the first few years.
I would encourage you to get some real exposure to the industry, while still researching, learning design, watching for good deals on equipment, etc.
Just my 2 cents... and BTW "Thank YOU".