in my experience:
1. 300x250 square works best.
2. the above works a better ctr with help from the heatmap
3. Camouflage. Thats blending in for those who dont know. Blend ads to look like its part of your content
4. Experiment with channels. Practice makes perfect.
Overall, a good site with unique content works best. Im not a supporter of MFA sites (made for adsense) but you can try that too.
