Best practices in building a client base

Hello all,
I’ve recently begun to do work as an independent contractor. I’ve been in networking for seven years and I provide my services (recommendation, implementation, and support) to smaller businesses.

My question is, how can I go about finding clients without spending a fortune on advertising? I have mostly worked for enterprise customers before and I had a sales force selling my services. Now, it’s an interesting exercise for me to figure out how to market and sell to the companies I’m targeting (basically anyone who doesn’t have a network staff).

Does anyone out there have any best practices on doing just that?

Thanks..