When I started writing I was heavily reliant on Get A Freelancer for work and my client portfolio blossomed from there.
GAF is just one of several sites that provide work, and we have already covered others such as Guru.com which offers in my opinion, better work, better pay but you have to have something to offer if you stand any chance of competing.
Other sites you can take a peek include the following:
This is a didactic resource filled with help and material to help you get your self organised but light on actually bringing writers and clients together.
Probably the best resource for getting you on the straight and narrow with taxes and accounting as well as providing good information on copywriting rates of pay.
Freelance Writers
This is a site that does bring writers and clients together and registration is required. A fee is payable which varies depending on the level of service you are using, but on the upside there are no commissions deducted from payments to you for completed work.
This follows a standard format of projects being posted and writers bidding on them from which a winner is selected. A unique selling point is that this is not a database driven site and it is more of a directory i.e. when you communicate with the website you are dealing with a person at the other end not an automated set of database instructions. This is supposed to help you position yourself and your work more effectively.
This site is a cross between those two above. It is packed with information but targetted at international writers and commissions. This site acts more as a listing site where your services are given a window onto the world and if someone is looking at commissioning a piece they will contact you rather than a bidding mechanism.
For $30 or so you get an entry in their writers database for the year which compares well with $12 per month for GAF as a Gold member (which you need to have if you expect to win any real work).
I have also found another website which I find useful for finding freelance jobs. It works in a similar way to the sites you have mentioned where by you pay small fee to bid on the jobs. They have quite a number of writer, copywriter and other jobs on at the moment.