Do you want to jump in right away? I would suggest either working at nights and weekends or getting a third shift job and then opening your garage for regular hours. All those hours are tough but you would be assured the bread money would still be coming in. I started slow while still keeping at least a part time job. I now realize back in the early days I never would have made it. Not because of any less knowledge of cars, but the few first slow years I learned so much about actually running a business, dealing with customers, and utilizing time correctly.
I'm spoiled, I work for me. And I love my boss. I don't think I could ever go back to punching a clock. The stress is pretty high sometimes but the freedom is great!!!!