A few observations: There are a lot of capable technical people out there that you would be competing with. Many are in countries like India, Pakistan and the Philippines and willing to work at a much lower hourly rate than we would normally expect in North America. Have a look at ODesk where you will find a lot of jobs posted and people posting their skills and rates.
Potential employers are often looking for people with a broad range of skills and meaningful experience. If you look at some of the ads on Craigslist or Kijiji you will probably see that pretty quickly. Some of the ads read like vegetable soup. Whether they find people with that range is hard to say.
There are some jobs where you can focus and don't necessarily need quite the same range of tech skills. There is some demand for people to configure and maintain Content Management systems like Wordpress and Joomla. There is also demand for SEO people who have a different range of knowledge and skill and it is less technically intense.
Working freelance on a project-to-project basis is pretty challenging since you never know where your next paycheck is coming from and you need to be constantly marketing and providing responses to ads while trying to get the work done for the current project. Having some ongoing customers is much more secure if you can find some.
The initial learning curve will be pretty steep and it will take quite a bit of time (actual as well as elapsed) to become competent enough to start advertising your services.
In order to gain some experience and maybe a reference or two, you might consider doing some Open Source work (e.g. join a project) or do some (free)work for a not-for-profit organization where they will provide you with a reference. This is obviously only applicable once you get past the initial learning curve.
I think that the starting point might be to do a regular scan of the job posting boards to get a feeling of what you would be diving into. It will give you a feeling for the types of jobs that are available, what the expectations are and what kind of pay rate you could expect. That might help you to decide if this is a path that makes sense for you. It may also lead to some more questions in which case you can bring those back and post them.