My Adsense Lessons

Hi everyone.
Because Adsense is one of my best earners, I´d like to share some lessons I learned with my experience. Hope they´re useful to some.

~ Ad placement - This issue is very important to have good results, check out Adsense website for advise. They have a map with the best ad placement spots.
In my blogs, the ads that work best are on top, the first third, below the header and on top of the sidebar column.
My most clicked ad units are horizontal lines, sidebar squares and buttons with links. I think the colours used in ads also have an important role. In my experience, the more ads look like normal links embed in the blog, the more they are clicked. I try to use ads with the same or similar colours of the blog. I normally use black or dark grey links but the background of the ad unit matches my blog´s main tone.

~ Traffic - Traffic is the key to conversion. In theory, a higher number of visitors converts in a higher number of clicks. Well, this isn´t always true. You can have many visitors and little or no clicks, like what happens with EC. It all depends on the visitors.
I have this theory that webmasters and bloggers don´t click in ads much (they´re adblind) but I can´t be sure. It´s only a theory of mine.

I think this is the real "Adsense Secret": If I knew what motivates people to click, I would make a living online.

This topic is interesting... I wonder why people click on ads?
Is it because they didn´t know that was advertising or it´s because they were interested in that specific ad´s content?
Is it because they haven´t found what they were looking for on my blog?
Well, it´s impossible to know what´s on people´s mind and what motivates them to click. If I had the chance to do a survey to the visitors of my blogs that click, I would probably have an idea. I just don´t have the chance to ask them anything.

In a recent post, I shared my experiences with my art blog. This blog is my best Adsense earner and most of it´s traffic comes from Google search engine. I don´t need to move a finger to have a few hundred visitors every day. Those visitors click but how can I know why?

In sum: I think it´s not easy to make a good income with Adsense. If you have a website with the best paid keywords and tons of visitors that click, you can consider yourself very lucky.
If you´re not in this lucky minority you can always research to find good niches, check Adwords PPC values and build several websites or blogs around the topics that pay well but have less competiton.
When I first started blogging I didn´t have a clue about how Adsense works. I though that Portuguese blogs wouldn´t be a good investment but I was wrong. After researching (and reading all instructions in Adesense and Adwards websites) I think I learned a good lesson.
Currently, I run some blogs that have SE traffic and visitors that click. Having various blogs in different niches was the solution I found to have better earnings and I´m working to improve even more.
Care to share your experience?