Post-its work great if they have a perfectly flat surface, but they're stiff enough that they'll pull up over curving contours (say lengthwise over a wing). Since I do my NMFs with Alclad, I use heavily de-tacked Tamiya tape and it works great.
Newspaper and tissue paper (the gift-bag kind, not kleenex) would both probably work quite well over more fragile NMF finishes.
On the Bench: 1/32 Trumpeter P-47 | 1/32 Hasegawa Bf 109G | 1/144 Eduard MiG-21MF x2
On Deck: 1/350 HMS Dreadnought
Blog/Completed Builds: doogsmodels.com