Here are a few things I learned:
I tried taking big jobs and never made as much money as when I took many small jobs.
If you are not a sales guy then find one. I was able to work all day and sell all night but that can ware you down fast.
Advertise no mater what you think and when you have no work and money that is the time you need to advertise most. Advertise consistantly, this way people that are looking see your in business and stable.
When you are busy advertise more and raise the prices a lot, you get better jobs and smarter clients
When you have no work give one job away at cost to keep you working, it will give you something to do instead of all the free time worrying abotu how to pay bills.
Do not undersell yourself. Most people, even thought they say they want the job for less, always think they get more when they pay more. You will get more work this way in the long run, of course you have to be able to deliver on quality workmanship).
Find and pay a good accountant, give as little money to the government as possible.
Find someone you trust that you can off load wok to if you get to busy to meat deadlines
Always return phone calls even if it is to say your to busy to take new work.
Always price a job even if you don't want it as long as you have the ability to deliver, price it high ..real high but put a price in, you never know
Well thats a few of my thoughts, I have more but I am starting to ramble I think. Good luck
In truth I would try to never turn something I love into work. If you don't like your day job then find a new one. Running a business is a lot more work than most people realize, but there are many good rewards to having your own business but money (even if you make a lot) is not one of them. <smile>