I wrote a book on
marketing a small business back in 1994 - its now available online.
Its pre internet so it has a lot of "offline" tips and tricks, its still very relevant.
I have run web design company for over 11 years, my wife and I started it in our living room and today we have 8 full time employees.
I would get your company site started ASAP (before you quit) and get listed in all the wqeb design directiories like
Freelance Designers
DesignFirms
http://www.webdesignplaza.com
http://www.marketingtool.com
hook up with some local hosting companies, write a blog about your city, the BBB and Chamber aof Commerce can be a good place to meet other local business owners.
You can build up your leads from sites like
DesignQuote.net
http://www.quotecatcher.com/
It can get stressful if its your only source of income and it takes time to build up a clientelle so be prepared - but its totally worth it, I couldn't live any other way :)
If you want to see my company its
http://www.vexcom.com/
Good Luck!