You need to have a minimum $50k liquid cash for incidentals, another $100k or more in leases for machinery. After that you must have at least your first years salary set aside. If you can cross those hurdles then start looking for a hole in the market place. Find a building and form an LLC. Most landlords will give you a month or 2 without rent to set up the shop. Then be prepared to pay in the area $0.15 to $0.90 per square foot of area leased. While your in you setup stages hire some sales reps or get out there and pound the streets for customers. Oh, and ones that will actually pay you. Most cases if the customer comes looking for you its because they already have exhausted there credit with another shop.
Just my $0.02 but it would make a lot more sense to take your skills and work in a shop that is already set up. Get paid (if well skilled) between $60-100K a year with insurance. Work 40-50 hours a week instead of 70-100 for much aggravation.
Success is the ability to go from one failure to another with no loss of enthusiasm-Sir Winston Churchill