Adwords FAILED for me
I had a go at AdWords, and ended up spending several hundred pounds - for precisely zero sales. I didn't go into it blind or expecting it to be easy, I did a lot of reading, monitored the keywords and got precisely nowhere.
The 'great' thing about AdWords is you can monitor what people are looking for and hone your campaign. The bad thing is you have do not a lot of space to explain yourself, and it is all too easy to get impressions to become your goal and to forget sales is the end result.
It seems OK to begin with - first couple of days (impression-wise). You get hooked, spend all your time staring at the stats and thinking you can tweak. You get dragged in and waste time and money.
But a single magazine ad - a similar cost - paid for itself several times over. The reason? I got to explain my product, I could precisely target the demographic. And tracking? Easy, offer the reader something in return for telling you where they found you.
Not rocket science, but not something Google want you to hear.