Everyone is making sites, blogs and other online applications. Most of them having target to make money online using these sites or applications. Maximum people preferred to sign up for advertising program to make money. Though they get traffic diverted, they earn money. Google Adsense is one of the popular program to make money. In adsense there are different ads like text ads, banner ads. I think banner ads are having more effective than text ads. Means banner ads get more clicks rates than text ads. I have written in one of my previous blog for effective banner advertising. http://moneybanner.wordpress.com/200...r-advertising/
Banners are more eye catching than text ads. It is also important to pick up a proper banner size and style to suit our site. And you have to properly place these banner on site. Also choose different style for banner than site. It may increase your click rates. The Site style banner may not easily catched by people. Also select the best fit banner on site page placement. Here are some examples of placements on a page https://www.google.com/adsense/static/en_US/Banner.html .
Google is advancing adsense algorithm to place relevant ads and detection of fraud clicks. So you should also take care of page quality. These factors affect your earning because we never know how Google calculates clicks and their rates.