Don't forget to ask for referrals. Ask for them, but don't just ask to be referred. With a client, for example, you might want to set aside a moment to talk after the successful conclusion of a project. Ask them who they know that hires designers, and ask whether you can mention the client if you contact them. They'll probably say yes.

You may not have a list long as your arm, but these leads will have a much higher conversion rate--even if sales are not immediate. If you mention your client referred you, they'll be the most likely to respond positively to your outreach. Iif they don't need you at the moment, they're more likely to get in touch with you when they do, because of the connection you have with someone they know and respect.