What is Adsense?
Where to place ads?
The best place is where people are looking at when visiting the website. The best place is usually on top of the pages.
What is the best ad type?
As stated above, there are image and text ads and also link units. The latter are great if space is limited. According to the authors experience, text ads work best, followed by link units. Ads should look like as if they were part of the websites content, hence the same colors (and fonts, font sizes) have to be used. To let the ads look fully integrated, borders should not be used.