I started on the same grounds, turned down loads of work over the years so gave it a crack. You soon realise though that all that work you had turned away needs to happen consistently month, after month and people actually need to turn up when they say they will.
Be as diverse as possible, I am predominently an Auto Refinisher so concentrate on anything bodywork, so valeting through detailing, PDR , SMART repairs, accident repair, custom paint, restoration and wheel refurbs.
However, by having powder coating facilities for the wheels I also do bike frames, swing arms etc, recondition tools for a local tool merchant as well as various other bits. Also, having tyre machines I also supply and fit tyres as well as take on service work and punt MOT's through one of the garages I do bodywork for.
Happy to share what I have gone through over the last year, what's worked and what hasnt. I am sure you appreciate the amount of work it takes to get such a venture off the ground and the fun can sometimes be replaced with some stress and frustration.