Hi Kevin
You`re getting some pretty decent advice here.
But here are some things to help you.
1) Find out about your local rules related to office in home. Some areas require a separate license.
2) Get your business license for your town. And if you`re planning to do a lot of work in a different, more affluent neighborhood, see if you need another license in their town.
3) Get business insurance on your vehicle. Don`t scrimp just because personal insurance costs less. If anything happens while you`re working, they won`t cover your claim.
4) Get an accounting or record-keeping system. You can do it on computer, or you can buy one of those Dome Bookkeeping Systems for just a few bucks.
5) Make sure you get an invoice pad with duplicate invoices so all your billings are in writing - and you keep a copy once you`ve given your customer the invoice. When they pay you, mark the invoice paid with the check number (or write CASH) and date paid.
6) Pay for all your costs by check or credit card so you have a good record of your expenses. If you must pay cash, keep your receipts in an envelope or box in the car and write them into your books each evening, or each week.
7) And Seafarer asked about making estimated tax payments. She`s right. You will need to do that. You`ll find details here on TaxMama.com about how to make estimated payments, when and what forms to use http://www.taxmama.com/Articles/es.html
This should give you a good start.
And, oh yes, read IRS Publication 334 - For Small Businesses http://www.irs.gov/publications/p334/index.html