Go to google, type in "web agencies [yourLocalCity]", make a list of the agencies, go on linkedin and try to find their technical director or lead developer or even the head honcho if they're small and get their name. Phone the main number, ask for that person, when you're on the phone with them, introduce yourself, say you're a new freelance dev with XYZ skills and ask if they would have any need for some extra resource. Try to get a meeting in person as you'll stick in their head more. Be ready to send a CV and/or body of work.
This works really well if you dont want to deal with end clients. You should also phone them every 3 months to remind them who you are, send them christmas cards, show them something you've done recently, etc. You can also replace "web" with "marketing", "advertising", "development", "design" etc in the initial google query.
If you're not an idiot and you're reliable and cost effective, this is a VERY good way to get regular, long term work.