Because I realised that I'd been wasting moneyHow come?
I no longer do any SEO/SEM work for anyone as I have now moved into the hosting sector. Any SEO/SEM is for my own projects.
Awww, thanks you guys.
One little thing I forgot to mention in that post is that minimum required CTR is lower for different match types. I'll say no more.
As for a resource, I have read the following blog three times over:
Random Musings about making $$$ on the net.
This guy knows his stuff and each post has some really golden information.