I feel where you're coming from, but I was told by one of the best in the business (Bob "Hollywood" Wagner) personally that there is no money in hydraulic install in cars. He told me to have another skill (engine building, painting, interiors, etc.). Because you'll go broke relying on installing hydraulics.
I suggest you pick up another trade to go along with your welding. Then build your own car to show off your skills. Just opening a shop and placing an ad in the Yellow Pages will not get you off the ground. People are not ging to pay you to experiment on their cars.
Just a suggestion.
Tyrone