Some guys like a dot of black electrician's tape, some neutral masking tape, some semi transparent scotch type tape. I have evolved to the semi transparent. I have used all three and had good results with all. The grease or vaseline has not been satisfactory because I am a hot weather shooter and continually clean my lenses. The concept just doesn't work as well if I don't place the dot accurately and permanently. If you use the dot for hundreds of rounds of clay target practice, you have to use the same system when you go hunting unless you want to revert to closing one eye. There is nothing wrong with wearing your shooting glasses when you are hunting and the dot is there for you. It all depends on how badly you want to hit them.
