Yeah, the nose pinch is an effective one. Usually you want to have a sequence of around 3 just in case one fails. I use the nose pinch, looking at your hands then trying to put your finger through the palm of your hand if I don't need to be inconspicious.

If I'm trying not to get noticed then I just pass my hands somewhere into my vision and count my fingers out of the corner of my eye.

You could also try Naiya's way of reality checking where you question yourself and your surroundings by asking yourself how you got where you are and if you remember putting those clothes on etc. The link to her post is here