My conclusion is slightly different to theirs. I have found that the best two positions, that work for me, are as a leader advert (i.e across the page under the blog's title) and at the top of the right hand column.
for placing AdSense, according to Google.
Regarding colours I have found that it helps to change them occasionally if you have regular readers and lots of subscribers. Unless things are altered now and again regulars tend to get 'blind' to ads. It's one of the reasons I have stressed the need for regular new blood to make money.
As I see it adverts above the fold work better than those below. I've tried the same sized ads lower down a column and these aren't very worthwhile but put the same ads at the top of a column and 'ding' more clicks.
I've also never had much success either with those above the page footer as Google suggest.
As I have said these are what have worked best for me, you may get differing results, but I thought I'd pass them on. It's really down to experimentation and the design, number of columns etc that your blog has. It's difficult to generalise.
Good luck,
Mike
Blogging Good Blogs. Read the way to blogging success.
Mister Linker for free links.
