Marketing your small business: How did you find me?

In my business, I use very strategic advertising to market my business, along with many unpaid forms of marketing like blogging and participating in online communities. Whenever I receive an inquiry about my services, one of the first questions I ask is: "How did you find me?"

This has been one of the best moves I could have ever made regarding my marketing and advertising. No longer do I wonder if a particular piece of expensive advertising is helping my cause. I know exactly which publication or search engine sent a potential client my way.