I usually just grab a nice handful ofdirtevery half hour or so and chew it for a little bit. The abrasive nature of the dirt does wonders for your teeth, and it really covers the natural scent of human breath.

I read somewhere that the indians used to do this to get close to whitetails and bison once the foliage came off in the winter.

When you think about it, you're covering your breath with dirt from the deer's home range. He is used to that smell, and won't be alarmed by it. Moss or treebark works fine too.