I'd avoid a job in a new shop. It's alot of hassle, little work, and uncertain future. I was the first person on the payroll of "On The Road Again" auto care center
(LINK) . While the idea was great and I loved working there, it was alot of stress, scraping by, referring people to the shop, and finding work to do.
Starting a shop of your own also takes lots of $$$, a good reputation, lots of advertisement and LOTS of $$$ for equipment. Unless you can afford the computers and training to work on modern computerized cars (and hybrid cars in the future), opening up an independent shop in this day and age is not worth the stress and risks. The shop I started for took out a $200,000 loan just to get off the ground.
Don't expect to become a master just from going to city college/vo-tech. It's good to get the basics to get you going, but you have to get *real* experience on your own in the field.
Remember, reputation is everything!