When you login to Google through the AdSense login you can get to a
page that contains a series of optimization tips. Although this is a
useful page, it can take awhile to read through. So let me present you
with a no nonsense quick overview of these tips.

The first thing that Google recommends is that you keep track of all
changes and test the performance of your ads using channels. You can
set up a number of channels using the Google statistics. This enables
you to track the performance of, for example, different ad formats,
different ad colors, different ad sizes and even different pages.

You can create channels that are specific to an ad format or you can
create a channel that is specific to a page on your website. You
definitely need to create channels because it is one of the best ways
to continually tweak and improve your AdSense performance and boost
your AdSense earnings.

Next it talks about where you should place ads on your pages and it
includes what is called a heat map, showing you the hot spots on an
average website. In general, it's common sense if you place ads
towards the center or upper regions of a page as you're likely to get
a better response. Placing ads on the right hand side, at the top
right hand side or at the very bottom of a page leads to very low
response rates.

Your best bet, in terms of getting the most click-throughs, is to try
and make the ads become part of the content. Place the ads right in
the middle of the content or place your content around the ads. Also,
if you use ads that blend in with your site you'll get a far better
click-through rate.

It then talks about using multiple ad units and whether or not you can
do this effectively. My experience is that pages for forums, for
example, perform particularly badly. I've yet to find a way to use
AdSense on a forum and generate a significant amount of revenue
without first annoying all of the forum's users.

Obviously, one of the biggest questions you need to ask yourself as an
AdSense webmaster is which ad format to use. Google gives you a
massive selection from skyscraper-sized ads to standard banner-sized
ads and really it will come down to testing. The more you can test and
the more you can judge by the results, the better your conversion
ratio and click through ratio will be.

You may also want to experiment with link units. As opposed to
straight-forward ads, link units contain a series of links through to
further pages of actual ads. So for example, people may click on a
link unit that says 'click here for ads about shopping'. You only get
paid, not if people click on the first link, but if they click a
second time on an actual website. Again, I've tried these and not
found them to be amazingly successful. But I haven't tested them
extensively; you will need to do that.