#1 - Not using ChannelsI didn´t make this Adsense error but if you aren't using Adsense Channels you are losing money and don´t have a way of tracking your development. If you don't believe me, set up at least URL channels for your pages and you'll see in real time what works and what does not.
#2 - Using the horizontal format
So far, the results are much better when people use the vertical format.
#3 - Placing Adsense Ad Units on the top, bottom, right and left of contentThe Adsense publisher community may not totally agree, but don't hide your ads by neatly stuffing them on the borders of your site.
Put your Adsense Ad Unit in the middle where your visitor will be forced to see them. It's not that your visitor doesn't want to see the ads it's that over the years of web surfing we've become blind to
traditional banner locations.
#4 - Adding your sites to the filter out listOne Webmaster thought that the way to let Google know that you wanted to add additional sites to your AdSense account was to list the URLs under the Advanced options tab. In reality, this tab is used to list the sites you want to filter out (i.e., not display AdWords) on your site. Google automatically knows what pages you want to include under your AdSense account when you add the code to the pages.
So, you can add any site you own without additional paperwork.
#5 - Not testing.Because of the limited information Google currently supplies, this can be difficult. Nonetheless, you want to see what works and what doesn’t on your site. Experiment.
#6 - Applying too early.If you don’t have at least 20 good content pages and some traffic, you’ll most likely be rejected.
Not applying because you believe 'this isn’t for me'.
Sure, there are situations where using AdSense doesn’t make sense.However, we believe that AdSense will benefit many people who currently have decided the program isn’t for them.
For example, we’ve heard from a number of professionals who feel that having AdWords on their sites will ‘taint their image.’ That’s possible, we suppose. However, we believe that for most
professionals, the added credibility gained by having ‘Ads by Google’ on your site (and the correct assumption by visitors that Google has therefore checked you out at least a little), more than compensates for this potential downside.