Most authors carry out some of their book promotion activities, both on and offline, in areas hosted by some other private entity. One example being brick-and-mortar bookstores. It seems to me that the first rule of hosted promotion is that the event or activity should be of mutual benefit to both the author and the host. This win/win approach makes for a well-supported event and a host who will be glad to help out you (and other authors) in the future.
I was at my local Borders branch today and I saw two examples of a self-published author promoting their work. The first one I saw was this flier. The poster does not clearly identify much about the books except that some random quoted people thought it was really nifty.
But the kicker for me was that the author put up a poster in a Borders store suggesting that people go and by this book from another vendor. In my opinion this simply isn't a good look. If an author chooses to cut non-Amazon vendors out the supply chain by printing and distributing via Createspace/Amazon that is their choice. But they should not expect to make their bed and then go promote in somebody else's.
On my way back through the store I came across Joseph S. Meraz with a well-placed official authors table covered in the big read Borders tablecloth. When asked he could sum up his book in a few sentences, briefly covering both plot and theme (i.e. what the book is about and why I might want to read it.)
Book signings for less-than-world-famous authors are always rather "quiet" affairs but Meraz had a good position, a nice manner, and a stock of books ready to go through the till and get signed. Kudos for keeping things classy. (And yes, I did purchase a copy).