Adsense Experimentation Is The Way Forward
Type in Adsense into any search engine, scroll down and you'll soon see a plethora of sites, pundits and ebooks offering to help you make your millions from the ubiquitous Ad program. I find it incredible how many such people and organisations can blandly eulogise on Adsense Optimisation with little consideration or disclaimer for the largely subjective nature of the topic.
Yes there are principles which are helpful and we will be exploring some of these in the weeks to come, but what applies to one site may not necessarily apply to another. You'll note that I try to be careful in my posts to point out that useful info on the topic is a "guide" or "helpful advice" and if I don't do this, tell me so!
Do your research, collect hints and tips by all means, but your own experimentation and exploration is key to optimising your own Adsense revenue.