If you have trouble figuring out which section of Genealogy shelving your book is on, please try going by the main subject of the book.
Shelving is by New books, general resources, religious resources, geographical area (non-US, then US states), wars and military, family names, oversize books, and periodicals. Shelves are clearly labeled, with a guide to shelving location on the endcap on each row of shelves.
If you have trouble determining the main subject, or if the book isn't located at the subject you thought it would be, please consult the Master List for shelf locations.