You can  use special  thin paper called " déco patch" (to be obtained in Arts and Crafts Stores ). It is much easier for the children. You cut small paper rectangles for them to put on the boxes alone.That paper is expensive.
You can also use tissue paper. (which is easier than paper napkins and less expensive than  “déco patch”paper ) but there are no motifs on  tissue paper.You can add the motifs of towels or those of "déco patch".