The AdSense Code Book Review
Joel Comm describes himself as an internet entrepreneur. That's a pretty generic title, but it's probably as good a phrase as any given that he creates and monetizes websites, writes books, and participates in the conference circuit.
Joel is also the author of The AdSense Code, a book about getting the most out of Google's AdSense program which I read recently. Don't even bother with this book until you've got a site with substantial content and ideally a steady stream of traffic. Much of what Joel recommends requires that you run tests to measure results and you can't do that without traffic. My preference was to wait for each tweak to be viewed 1,000 times (i.e. 1,000 ad slot views) before making conclusions.
Joel's recommendations are good though. Largely because as you read through the book you can't help but think of things worth trying. A couple of co-workers of mine found the book inspirational too with one saying that he's going to pick up a copy of his own. In addition to trying out different ad sizes, ad placements, and blending techniques I also received confirmation that hypotheses I had formulated on my own were indeed valid.
In terms of skill-level, this book is for the intermediate website owner. As I alluded to earlier, you should really focus on your site's content and traffic before worrying about tweaking your ads. Some people even recommend launching a site without ads to avoid scaring away new visitors. That choice, of course, is yours. If you're just beginning to think about starting a website of your own, check out my Make Easy Money with Google review.
I recommend you check out Joel's blog where you can learn a lot about AdSense optimizations just by reading his posts and by looking at what he's done with his own site. Try not to be turned off by the annoying floating ad that appears when you first visit the site.