Here are some very important advices for adsense newbies.

1)- The mos effective adsense format is square box (250*250).
2)- The ads should be inside the page rather than in the upper part.
3)-The ads color should not be similar to the colors of the website. Is better to have them different, so the visitors can see them.

4)- One ad box with only 3 ads is preferable to 3 ad boxes with 4 ads, because only the best paying ads are displayed.
5)- For more incoming is better to create pages targeting high-paying keywords (finance, seo, bank, etc.)
6)- The link ad unit format is effective.