Some pretty good tips on using AdSense in your blog come from SelfSEO, like this:
Internet users are "trained" to look in certain locations and ignore things that are outside of thier narrow scope of vision. People can look to the sides for information, but the propensity for them to click your ads becomes significantly lower. By putting ads directly "in thier face", you have a greater chance they will click it.
Here's a few more tips:
I use a white background instead of a color background.
I remove the border on adsense so it does not look like an ad and make sure it matches the background.
I keep the Title and the Hyperlink "Blue".
I keep Adsense "above the fold", so they are the "FIRST" things that people see when they arrive at the site.
I try to keep the ads "left" aligned.
I use the 160X600 vertical for people to see when they move vertically down the website page.
I try to place images near the google ads. Images draw the eyes near the ads.
I keep the site concise, clean and focused.