patio11 talks about it some in his writings/podcasts/etc.
Brennan Dunn talks about it heavily in his Consultancy Masterclass.
But here is a tidbit for free.
Join your local chamber of commerce. Set up a small seminar on a topic closely related to what you do. Invite local business owners to it (do it for free if you can, or charge a small amount..depends on how well established you are).
GIVE THEM ALL THE INFORMATION THEY WOULD NEED TO DO WHATEVER IT IS YOU ARE TALKING ABOUT.
Pass out your email address, and let business owners contact you. You will have stablished your knowledge and authority, and even though you gave them a 4 hour speech on how to do internet marketing (or whatever), they wont have the time or comfort level to do it themselves...but now they will know one person who can.
Just one way to get started.