Offer your services free of charge to local schools, clubs, knitting circles - it doesn't matter. Get some sites under your belt, get a portfolio site up, register with every designer list you can find, Yell.com and Thompson's Local online.
Get your site optimised for search engines, and tell anyone and everyone what you do - friends, family, the milkman... EVERYONE.
Be honest about what you can and can't do - people will respect you more, and find you more trustworthy.
It takes a while to build up a client list, but you're on to a winner when you start getting repeat business. One of my clients offered to set up a monthly standing order to cover his maintenance costs...!
The point is, without a portfolio, no-one is likely to employ you. You need to offer your services to people who need them - they get a 'free' website, on the condition that you can put your name to it and use them as references. I realise it's annoying to work for nothing when you start out, but the more sites you do, the more clients you'll attract (provided you're any good!). The word-of-mouth thing really is true - hopefully you will eventually get to the point where you can become selective about the jobs and clients you take on. I work full-time, and only freelance off my own back, but I find myself turning down jobs I don't like the look of, partly due to time, and partly because I have the luxury of being able to do so.
Just stick with it, work hard and you'll get there in the end. Good luck!