Mr Williams,
Color, type size, and placement key to good signage. Also, easy to go overboard and have too much. Yellow is very good color for the lettering that goes onto the sign. Blue is a relaxing color.
Re parts of the collection to sign? Let your circ data make that decision meaning sign the more popular.
Also, placement, meaning height, is important. Since most adults will range between 5'4" & 6' a sign should be in that range. If you use say 5'8" then the midpoint of the sign should be at that height.
Dick Waters
(401) 556-2398