There are two ways to make more money from your website -- get more traffic or make more money from your existing traffic.
Google's Adsense program provides a great way for you to easily increase your current revenue, even if you already use it there are things you can do to increase your revenue with it.
In this article I am going to show you the methods I've used to double my own clickthrough rates as well as those of other website owners.
One of the things that set Adsense apart from other banner ad programs is your ability to customize the code to fit the look of your site, and the wide variety of unit sizes available.
Advertisers write ads which are then shown on your site. As an advertiser I can increase my clickthrough rate by writing good ad copy. This means more targeted prospects visit my site. I then have the opportunity to "convert" them into my customers.
As a publisher I can control the color and placement of advertiser's ads - but I can't control the words. So in that way there is a limit on what kind of optimization I can perform. I can't make advertisers write better ads afterall, luckily though Google is constantly analyzing advertisements and ones that do not get clicked on end up filtered out or shown less often. In the end though color and placement simply draw attention, but it is the words that create the action (the click), and the words aren't under your control.
However, there is an unpublished feature called Google Hints that does give you some control. It does not allow you to edit ads, but it does allow you to give Google help on picking keywords for your site. You aren't supposed to use this feature without permission though.
As far as changing the color and appearance of your ads, don't worry, you don't need permission to do that. In fact Google encourages publishers to experiment to find the best placement. After several months as a publisher Google mailed me a little book which gave tips on increasing my clickthrough rates. You can visit Google's website to see an illustrated heat map whichs shows the best places for you to put Adsense ads.
There are two different "theories" on how to place your Adsense code. One says blend it into your site, the other says make it stick out. My own experience has shown you need to blend it in but make it visible. By that I mean that you should blend your ads in enough so that they do not look like banners (which people tend to gloss over) but yet you don't want the ad to be too hard to see that no one clicks on it.
What approach do you take when building a new website? Do you create a nice layout and leave extra space for a few banner ads? This is the wrong way to do it. It is critical to think about Adsense when designing your website. If you want to maximize your earnings you can't just make a fancy design and plop the Adsense code in as an afterthought. By planning ahead you can insure maximum placement effectiveness. I specifically made a recent site with Adsense in mind. The result? Earnings 5 times higher than what I had predicted them to be.
So how is a website designed around Adsense? Match Adsense's font - that includes the size and color. Get rid of the CSS mouseovers on your links and make them plain and boring -- like Adsense. Also think about placement as you build the site.