AdSense is so simple and complex at the same time. I learned a lot from AdSense Help pages, AdSense Google Groups and Youtube videos offered by AdSense team.
Now the same team is offering free online webinars for the same purpose. These webinars focus on specific subjects or topics like increasing your revenue with the AdSense. The other advantage is that you will be able to ask questions at the end of webinar on the topic.
There are more webinars planned for 2009 and you can register for them at AdSense.
Inside AdSense: Connect with AdSense via online webinars