I use Pinterest as publicity for CAN-CON 2014, a science fiction con I am involved with.
The main thing I figured out is that the words beneath your pin should refer to the thing in the pin, and also give the message you are trying to give.
Pinterest doesn't really see pictures. Which makes sense. It reads captions and that is how people find your pins and your Boards.
I was getting lots of likes and even repins, mostly of Nathan Fillion because; Nathan Fillion, but that wasn't useful until I started noting that he had absolutely no knowledge that CAN-CON2014 is scheduled from Oct. 3-5, 2014 in Ottawa and that our Guest of Honour is Jo Walton who won the 2012 Hugo Award beating out George RR Martin.
Now all those pins work for our Con. (and people looking for Ottawa, Martin, and Walton find them as well).
This is our Pinterest Board if you want to take a look.
http://www.pinterest.com/cancon2014/
