That's great news that you already found a client that way! 
please me too very quickly
I also took talkin's advice and have turned the ads off between midnight and 5am - 5am being the time people are going to start logging on and thinking "wtf am I going to do?".
I've just checked my account and it says it's displayed an ad twice but no clicks yet - fair enough, it's more a mon-fri thing so I'm waiting in eager anticipation now!
So now I'm going to be keeping a close eye on it and tweaking it to figure out what gets the best response.
As far as SEO goes, that was turned on its head a few weeks ago with Google's penguin update - and it now seems rather than just using a splatter-gun approach with keywords, Google would prefer you simply develop your site to be quality and deliver on what you do. Which tbh I'd imagine you do anyway. They're trying to deter niche marketing - not genuine businesses! You know, they were trying to get rid of those websites which do "false advertising" - you know, you click on it and it's full of ads for Viagra or something like that.
I've been commenting on industry blogs and the like and getting some referrals that way - and whilst it's a good way to make me more visible and get a good reputation - at the same time, people will only go looking for my work once they've already started investigating me iyswim. They (probably) won't stumble across my words until they know they have a problem.
Otoh, all advertising is good advertising right and it helps hone my though processes on the job in hand.