You know that posting duplicate content online is dangerous, but I bet you do it anyway.  

 You will get the most SEO value for your hard work if you rewrite the post for each blog you intend to use it on. But, I know that when you have worked hard on an article, posting it more than once is just so awfully tempting that it is hard to resist.

 So here are steps you can follow to use canonical link tags to identify duplicate content and hopefully avoid any Google penalties.