I suppose I am in a very similar situation, I run my own business and run it mainly off word of mouth.

Surprisingly I am finding facebook quite a good place to help that word spread, I was very reluctant to sign up, but it is really helping me get the word out there, to the point that 25% of my web traffic are now coming from facebook. I don't think it's a marketing tool as such, just an aide for your current clients to pass your details on. It's also a great way to let your clients know about an new service you are offering via links back to your blog etc...

I'm in the photography game, so maybe this won't be so useful, but I wouldn't rule it out as it costs nothing.

I was given advice to stay away from traditional advertising unless you have a massive budget as the consumer is so swamped with other adverts that your just won't stand out of the crowd.

Cheers

Cris.