Hi ... Does ad position (top bottom center left or right) can affect my adsense earnings ? I never paid much attention for this issue. Thanks
Yes, basically your ads should be placed on areas whereby it will get the most attention and easily seen. Try googling for "adsense ads heat map" and it will explain well on what you should expect.
Ads after title of post before contents. Or just look at those establised sites, and see what they are doing, after all they spent lots of time & hire experts to get things done for them.
Yes Google places the higher paying ads "above the fold" ie. near the top if you have multiple adsense ads on the same page.