Effective Craigslist advertising?

So, my company does many things. The prices are (relatively) low, and the quality of services is high. However, it's a young company, and I am promoting it.

Say that I provide SEO services. Very basic ones. Little bit of keyword research, title tags, meta descriptions and etc. Say that I charge $299 for that.

I've posted about 5 ads on Craigslist where I have this offer. I had the post read by a guy who claims to be an internet-expert (and I think he is), and he says that it's a good one - that it should attract visitors.

What I also did is go to Dex (yellow pages) of my city and send emails to many small businesses about my offer. I presume it was treated as spam, in 90% of cases.

What I also did (again) is contacting the people that posted on craigslist - people who had websites that sucked and needed some basic SEO. I offered it to them.

I have about 5 ads on craigslist (Seattle), and about a couple on USFreeAds and Kijiji.

The thing is, I never got a single assignment.

What am I doing wrong? Should I keep posting on Craigslist, but in a much larger number? Should I consider hiring someone to post 10 ads a day for me on CL? Will it eventually work?

Thanks!