How do I locate the ceiling joists in my kitchen addition?
I like the rubber insulated handle of my screw driver as a knocking tool.  The rubber handle of a hammer works well, won't mar the ceiling.  A small finish nail leaves very little hole behind. (Happy Hunting) I carry an electronic stud finder as well. The newer stud finders are pretty amazing, fab results.  You don't need an expensive finder for impressive results.  I would avoid the low, low end models.