An effective way to increase your client base is to participate as a volunteer in civic and professional organizations whose membership includes your target client. You'll make new friends while having an opportunity to demonstrate your competence. You'll also hear about new projects getting under way in your business community and increase the number of people likely to send you referrals.
The key to making this strategy work, though, is that you must contribute. No one will throw work your way if you show up looking like a hungry opportunist. Get to know people, do your share, make friends and THEN let people know about what you do for a living.
This strategy may take up to six months to start generating leads for you, but if you have real skills and can get across what you do clearly, and make sure that the groups you join do attract people who fit your client profile, you'll find it works far better than more obvious strategies like advertising or direct mail.