Though I'm not aware of any technical impact from where or how you choose to place social buttons, I've found the greatest share rates to be when you prompt the user with a call-to-action at the end of a piece of content. The best way to do this is with a box that slides in somewhere non-intrusively at the end of the article (if that's the content we're referring to here). There's a great tutorial for this here.
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RE: What is the best Practice for Adding Social Buttons to your Sites from SEO Perspective?