Hello Duathlete1,
I tried Post-It Note pads as well, but with me they have their own problems: they're just not sticky enough and blow away when I start spraying. It's also not possible to make them follow the shapes/ texture on models.
I use Tamiya Masking tape which I "grease up" a little by fingering the adhesive side of the tape: it gets less sticky and will be easier to remove. For bigger surfaces I use a combination of both: Post-It notes with masking tape just over the edges to get a good fit.
Good luck!
Gertjan