In a method of preparing the wrapping materials used to fashion packs (20) for tobacco products, typically cigarette packets and cartons, without installing extra machine units on the packer, a sliver (28) or continuous stripe (44) of pre-encoded or recordable magnetic ribbon (25) is applied to selected areas (29) of the wrapping material (21; 35), whereupon the material is divided into smaller strips (31) or sheets (37); these are then coiled into rolls (33) or ordered into stacks (42) of sheets (46) or blanks (41), serving as temporary storage units (34) that can be loaded onto the packer as and when needed. Each pack (20) will consist in at least one specific and essential packaging component (4, 8, 12, 13, 16, 19) obtained from the temporary storage unit (34) and bearing at least one sliver (28) or stripe (44) of the magnetic ribbon (25).