After nearly five months with having AdSense on my 2-column personal blog, this is my two most successful formats/placements: 336x280 in single-post views, faint CSS borders, right after the post *before* the comments 200x200 on the front page, no borders, top-right corner, first thing on sidebar Prior to me using the 200x200 I alternated between Google referrals and the 125x125. Neither of which yielded much success. I concentrated on optimising my single-post views because I write about a variety of topics: dating, relationships, current affairs, blogging/tech, clubbing and it is my single-post views that get landed on a lot via search-engines. The fact that the 200x200 work well for me was a surprise as my regular readers tend to be ad-blind. Currently my all-time CTR is hovering at 0.27% and am constantly trying to improve it. Just wanted to give back some ideas to the community and hope that this inspires you.
CTR 0.27% - that's almost nothing, it sounds strange that you can't get it higher than that. Average CTR for my websites is around 4%, some strugling with a 1% rating and others flying ahead with 10+%.
Like I said, am constantly trying to improve it. Plus I had a lot of channels set up from the beginning which diluted my all-time CTR. This month I've got it to 0.44%. And my blog is not about a specific niche which tends to make it harder. For now, I treat AdSense more as pocket-money - a bonus for my blogging hobby.