Place your adsense verification code propoerly. Always drop google codes on the index.html or index.php (home page) header tags. This is the preferable place to drop google codes.
Choose the right Ads to display. Google adsense gives you the option to choose between text, text and banners, banners only ads type. Also the sizes varies and one has the option to choose whether it be a vertical, horizontal or square ads.
Have some sort of disclaimer or well layed out website describing you and your services. Create pages like About us, Contact us, Terms of Service etc.
Infringement of images matters. Do not use copyright images. This is really a catch. Just modify and edit your own banners.