This isn't quite what you were looking for, but I'd say just go for it. If you still want a safety net, then don't quit your day job right away, just freelance on the side until you're more comfortable with it.

I do occasional side jobs, mostly through elance. They take about 8-10% of your income in fees, but they do a couple of things to make up for it:

* They have a good pool of work ready for you to bid on.

* They automatically charge your client's credit card each week if you've recorded hours. (And you can set up https://github.com/nfriedly/elance-withdrawal to automatically transfer it from elance to your bank.)

* You can differentiate yourself even without much experience by taking their skill tests.

Start your rates around $75 an hour and raise it up to $100 after you have 2-3 good jobs under your belt.

Don't get distracted by the folks charging ridiculously low rates - they are not competing with you, they're competing with each other for the clients who either don't need quality work or don't understand that you get what you pay for.

Oh, and put about 50% of your income into savings. Depending on your country, you might end up owing a good portion of that in taxes, and regardless, whatever's left makes for a nice emergency/rainy day/ vacation/retirement fund.

Feel free to email me if you want to go down that route and have more questions. (Or just post them here ;)