1. You should make your Adsense ads look as a part of your web page. They shouldn't look like an Ad. People are negative to advertising. They search the internet for content not ads. Especially for Banners - they have a less of 0.5% response. Their days are over. Imagine if you have an Adsense ad looking like the typical Banner with different colors. It will not be profitable.
2. Text ads are better than image ads. Like before, people are more responsive to text than images. In a way it is considered as a part of the online document and is more clickable.
3. No B ads. One of the best tricks is to erase the bs of Adsense ads and make them, again, having the same color with your website's background.
4. No other advertisements. The first reason is to be legitimate according to Google's Rules and the second more practical reason is that you do not want to distract your visitor's attention and go somewhere else without clicking your Adsense ads.
5. Placement. Even if you have the best Ad, people will not respond if they don't see it instantly. The best place to see the ad is the top of your web page and the next is aside your document's text. Visitors will click it more frequently since it will look like your text.
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