my phone and cord to charge it on the laptop
some cash for coffee
an open mind
When I get to the bookstore, I usually first do one of the following:
I take my findings to a table at the coffee shop and usually put a pad of paper and pen or some other item on top of them so people know that someone is sitting there (and so that, in the event that the staff happen to walk through during the next few minutes they won't re-shelve my hard won items).