Humans are very visually oriented, that is why, and this will not come as a surprise to you, your first impression counts. This goes for meeting someone of the opposite sex, but it definately goes for your website. On different levels even!
First of all it’s important that your website looks nice and clean, well structured, not messy (in my case, don’t make the website a copy of my desk: a complete mess with piles everywhere). Nobody likes to read and follow a website which looks like crap, with bad colors and bad navigation and layout.
The third level where this title fits, is in the same line as the second level (but not the first, great thinking huh? 😉 ). If you have multiple adsense units on your website, google will place the ads that are best performing in the first ad unit that they encounter! They know it too, the first impressionis very important. And they don’t particularly want you to succeed, but they want to auuccees, so they help you in this way.
Now, what does this mean? Well, google puts the ad that has won the adwords auction, and thus has the highest payout per click, first in your ad units. This means that (watch out! Math part coming!) if you get this ad with the highest pyout for your page, to show up in the ad-unit that has the highest clickthrough rate for your page, you will get the maximum revenue possible for your page! However, there is a small pitfall to watch out for: the first ad-unit is not necessarily the first ad-unit that shows up on your page, but is the first ad-unit that shows up in your code. Depending on the layout and setup of your site, CDs can trick you, and the first ad-unit to show up in the code can even be the last ad-unit showing on your website. So a minimum of codediving is necessary here!
I hope you found this article to be usefull, and if so, feel free to social bookmark it. Should you still have any questions, please feel free to ask them via the comments!